Gene Family Encoding Research Articles

Comprehensive profiling of endogenous phytohormones and expression analysis of 1-aminocyclopropane-1-carboxylic acid synthase gene family during fruit development and ripening in octoploid strawberry (Fragaria× ananassa)

The non-climacteric octoploid strawberry (Fragaria × ananassa Duchesne ex Rozier) was used as a model to study its regulation during fruit ripening. High performance liquid chromatography electrospray tandem-mass spectrometry (HPLC-ESI-MS/MS) was employed to profile 28 different endogenous phytohormones in strawberry. These include auxins, cytokinins (CKs), abscisic acid (ABA), ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), jasmonates, and phenolic compounds salicylic acid (SA), benzoic acid (BzA) and phenylacetic acid (PAA) together with their various metabolic forms that have remained largely unexplored thus far. ABA, ACC and CK N6-(Δ2-isopentenyl)adenine (iP) were found to be associated with ripening while ABA catabolites 9-hydroxy-ABA and phaseic acid mimicked the pattern of climacteric decline at the turning phase of strawberry ripening. The content of other CK forms except iP decreased as fruit ripened, as also that of auxins indole-3-acetic acid (IAA) and oxo-IAA, and of jasmonates. Data presented here also suggest that both the transition and progression of strawberry fruit ripening are associated with N6-(Δ2-isopentenyl)adenosine-5′-monophosphate (iPRMP) → N6-(Δ2-isopentenyl)adenosine (iPR) → iP as the preferred CK metabolic pathway. In contrast, the ethylene precursor ACC was present at higher levels, with its abundance increasing from the onset of ripening to the red ripe stage. Further investigation of ripening-specific ACC accumulation revealed the presence of a large ACC synthase (ACS) encoding gene family in octoploid strawberry that was previously unknown. Seventeen ACS genes were found differentially expressed in fruit tissues, while six of them showed induced expression during strawberry fruit ripening. These data suggest a possible role(s) of ACC, ABA, and iP in strawberry fruit ripening. These data add new dimension to the existing knowledge of the interplay of different endogenous phytohormones in octoploid strawberry, paving the way for further investigation of their individual role(s) in fruit ripening.

A chromosome-scale genome assembly of the Mongolian oak (Quercus mongolica).

Mongolian oak (Quercus mongolica Fisch.) is an ecologically and economically important white oak species native to and widespread in the temperate zone of East Asia. Here, we present a chromosome-scale reference genome assembly of Q.mongolica, a representative white oak species, by combining Illumina and PacBio data with Hi-C mapping technologies that is the first reference genome created for an Asian oak. Our results showed that the PacBio draft genome size was 809.84Mb, with a BUSCO complete gene percentage of 92.71%. Hi-C scaffolding anchored 774.59Mb contigs (95.65% of draft assembly) onto 12pseudochromosomes. The contig N50 and scaffold N50 were 2.64 and 66.74Mb, respectively. Of the 36,553 protein-coding genes predicted in the study, approximately 95% had functional annotations in public databases. A total of 435.34Mb (53.75% of the genome) of repetitive sequences were predicted in the assembled genome. Genome evolution analysis showed that Q.mongolica is closely related to Q.robur from Europe, and they shared a common ancestor ~11.8million years ago (Ma). Gene family evolution analysis of Q.mongolica revealed that the nucleotide-binding site (NBS)-encoding gene family related to disease resistance was significantly contracted, whereas the ECERIFERUM 1 (CER1) homologous genes related to cuticular wax biosynthesis was significantly expanded. This pioneering Asian oak genome resource represents an important supplement to the oak genomics community and will improve our understanding of Asian white oak biology and evolution.

Geospatial Paradigm of Nucleotide Substitution within the Gene Family Encoding Plasma Membrane H+-ATPase Pumps in Arabidopsis thaliana

The PM H+-ATPase gene family consists of 12 members in Arabidopsis thaliana denoted to Auto-inhibited H+-ATPase 1-12 (AHA1-AHA12). This gene family performs crucial roles in many aspects of plant growth and development such as ion and metabolite transportation, pollen development, stomatal opening, signalling process, and adaptation to abiotic stresses especially thermal changes. The H+-ATPase action dynamically fluctuates during thermal changes in order to enhance adaptation strategies in plants. Based on the fact that surface temperature on average is typically warmer in lower latitudes and cooler in higher latitudes, the association of PM H+-ATPase genetic variants (SNPs) with latitude intervals was studied using chi-square testing of 1001 Genomes project data. The results indicated a significant association between nucleotide substitution and latitude interval, and therefore a geospatial paradigm of PM H+-ATPase nucleotide substitution was established. A>T and T>A substitutions showed a close positive association with higher latitudes (cold climate) and negative association with lower latitudes (warm climate), and vice versa for A>G. Most of the nucleotide substitutions were associated with extreme cold and warm climates while cold climate had more impact. The most significant signal of PM H+-ATPase genes strategy for adaptation to cold climate was A>T nucleotide substitution. Also, the results showed that the most high-impact SNPs were identified in coding regions and related to premature stop codons.

Connexin Gap Junction Proteins in Development and Disease

Connexins form tightly‐regulated large‐pore channels that facilitate the passage of various ions, metabolites, and signaling molecules directly between cells, or in some cases and/or pathologies, to the extracellular milieu. The human connexin encoding gene family consists of 21 members and mutations in half of these genes leads to over two dozen diseases ranging in severity from manageable developmental abnormalities to life‐shortening organ failure. Developmentally, connexin expression and gap junctional intercellular communication begins at the 8 cell stage and persists throughout organogenesis resulting in most adult cells expressing two or more connexin subtypes. Connexin genes are exquisitely regulated during all developmental processes before birth, and in many tissues like the skin, after birth. Connexins regulate their function by channel gating processes and notably through their turnover owing to their short half‐life of only a few hours. Given their ubiquitous distribution it is not at all surprising that gene mutations lead to disease. In fact, it is probably more surprising that patients harbouring connexin gene mutations do not present with more clinical morbidities. Our laboratory has used tissue‐relevant cells, primary cells, organotypic cultures, mouse models of human diseases, and induced pluripotent stem cells from connexin‐linked disease patients to uncover ten distinct mechanisms by which connexin gene mutations cause disease. Collectively, connexin‐disease linked mutants have been classified into distinct gain‐ and loss‐of function molecular mechanisms of action. Our long‐term goals include developing strategies to compensate or overcome the cellular and tissue defects triggered by these mutants. This presentation will discuss how connexins have emerged as therapeutic targets in disease and in injury repair. We anticipate that once it is better understood how connexin gene mutations cause disease and abnormalities, which often present more acutely during aging, these findings could be translated into pre‐clinical studies leading to possible treatments for gap junction‐linked diseases.Support or Funding InformationSupported by the Canadian Institutes of Health Research.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The genetic architecture of colonization resistance in Brachypodium distachyon to non-adapted stripe rust (Puccinia striiformis) isolates.

Multilayered defense responses ensure that plants are hosts to only a few adapted pathogens in the environment. The host range of a plant pathogen depends on its ability to fully overcome plant defense barriers, with failure at any single step sufficient to prevent life cycle completion of the pathogen. Puccinia striiformis, the causal agent of stripe rust (=yellow rust), is an agronomically important obligate biotrophic fungal pathogen of wheat and barley. It is generally unable to complete its life cycle on the non-adapted wild grass species Brachypodium distachyon, but natural variation exists for the degree of hyphal colonization by Puccinia striiformis. Using three B. distachyon mapping populations, we identified genetic loci conferring colonization resistance to wheat-adapted and barley-adapted isolates of P. striiformis. We observed a genetic architecture composed of two major effect QTLs (Yrr1 and Yrr3) restricting the colonization of P. striiformis. Isolate specificity was observed for Yrr1, whereas Yrr3 was effective against all tested P. striiformis isolates. Plant immune receptors of the nucleotide binding, leucine-rich repeat (NB-LRR) encoding gene family are present at the Yrr3 locus, whereas genes of this family were not identified at the Yrr1 locus. While it has been proposed that resistance to adapted and non-adapted pathogens are inherently different, the observation of (1) a simple genetic architecture of colonization resistance, (2) isolate specificity of major and minor effect QTLs, and (3) NB-LRR encoding genes at the Yrr3 locus suggest that factors associated with resistance to adapted pathogens are also critical for non-adapted pathogens.

Evolution, functional differentiation, and co-expression of the RLK gene family revealed in Jilin ginseng, Panax ginseng C.A. Meyer

Most genes in a genome exist in the form of a gene family; therefore, it is necessary to have knowledge of how a gene family functions to comprehensively understand organismal biology. The receptor-like kinase (RLK)-encoding gene family is one of the most important gene families in plants. It plays important roles in biotic and abiotic stress tolerances, and growth and development. However, little is known about the functional differentiation and relationships among the gene members within a gene family in plants. This study has isolated 563 RLK genes (designated as PgRLK genes) expressed in Jilin ginseng (Panax ginseng C.A. Meyer), investigated their evolution, and deciphered their functional diversification and relationships. The PgRLK gene family is highly diverged and formed into eight types. The LRR type is the earliest and most prevalent, while only the Lec type originated after P. ginseng evolved. Furthermore, although the members of the PgRLK gene family all encode receptor-like protein kinases and share conservative domains, they are functionally very diverse, participating in numerous biological processes. The expressions of different members of the PgRLK gene family are extremely variable within a tissue, at a developmental stage and in the same cultivar, but most of the genes tend to express correlatively, forming a co-expression network. These results not only provide a deeper and comprehensive understanding of the evolution, functional differentiation and correlation of a gene family in plants, but also an RLK genic resource useful for enhanced ginseng genetic improvement.

Functional differentiation and spatial-temporal co-expression networks of the NBS-encoding gene family in Jilin ginseng, Panax ginseng C.A. Meyer.

Ginseng, Panax ginseng C.A. Meyer, is one of the most important medicinal plants for human health and medicine. It has been documented that over 80% of genes conferring resistance to bacteria, viruses, fungi and nematodes are contributed by the nucleotide binding site (NBS)-encoding gene family. Therefore, identification and characterization of NBS genes expressed in ginseng are paramount to its genetic improvement and breeding. However, little is known about the NBS-encoding genes in ginseng. Here we report genome-wide identification and systems analysis of the NBS genes actively expressed in ginseng (PgNBS genes). Four hundred twelve PgNBS gene transcripts, derived from 284 gene models, were identified from the transcriptomes of 14 ginseng tissues. These genes were classified into eight types, including TNL, TN, CNL, CN, NL, N, RPW8-NL and RPW8-N. Seven conserved motifs were identified in both the Toll/interleukine-1 receptor (TIR) and coiled-coil (CC) typed genes whereas six were identified in the RPW8 typed genes. Phylogenetic analysis showed that the PgNBS gene family is an ancient family, with a vast majority of its genes originated before ginseng originated. In spite of their belonging to a family, the PgNBS genes have functionally dramatically differentiated and been categorized into numerous functional categories. The expressions of the across tissues, different aged roots and the roots of different genotypes. However, they are coordinating in expression, forming a single co-expression network. These results provide a deeper understanding of the origin, evolution and functional differentiation and expression dynamics of the NBS-encoding gene family in plants in general and in ginseng particularly, and a NBS gene toolkit useful for isolation and characterization of disease resistance genes and for enhanced disease resistance breeding in ginseng and related species.

Development of molecular markers linked to disease resistance genes in common bean based on whole genome sequence

Common bean (Phaseolus vulgaris) is the most important grain legume for direct human consumption in the world, particularly in developing countries where it constitutes the main source of protein. Unfortunately, common bean yield stability is constrained by a number of pests and diseases. As use of resistant genotypes is the most economic and ecologically safe means for controlling plant diseases, efforts have been made to genetically characterize resistance genes (R genes) in common bean. Despite its agronomic importance, genomic resources available in common bean were limited until the recent sequencing of common bean genome (Andean genotype G19833). Besides allowing the annotation of Nucleotide Binding-Leucine Rich Repeat (NB-LRR) encoding gene family, which is the prevalent class of disease R genes in plants, access to the whole genome sequence of common bean can be of great help for intense selection to increase the overall efficiency of crop improvement programs using marker-assisted selection (MAS). This review presents the state of the art of common bean NB-LRR gene clusters, their peculiar location in subtelomeres and correlation with genetically characterized monogenic R genes, as well as how the availability of the whole genome sequence can boost the development of molecular markers for MAS.

Genome sequence of the cultivated cotton Gossypium arboreum.

The complex allotetraploid nature of the cotton genome (AADD; 2n = 52) makes genetic, genomic and functional analyses extremely challenging. Here we sequenced and assembled the Gossypium arboreum (AA; 2n = 26) genome, a putative contributor of the A subgenome. A total of 193.6 Gb of clean sequence covering the genome by 112.6-fold was obtained by paired-end sequencing. We further anchored and oriented 90.4% of the assembly on 13 pseudochromosomes and found that 68.5% of the genome is occupied by repetitive DNA sequences. We predicted 41,330 protein-coding genes in G. arboreum. Two whole-genome duplications were shared by G. arboreum and Gossypium raimondii before speciation. Insertions of long terminal repeats in the past 5 million years are responsible for the twofold difference in the sizes of these genomes. Comparative transcriptome studies showed the key role of the nucleotide binding site (NBS)-encoding gene family in resistance to Verticillium dahliae and the involvement of ethylene in the development of cotton fiber cells.

Molecular Characterization and Evolution of a Gene Family Encoding Both Female- and Male-Specific Reproductive Proteins in Drosophila

Gene duplication is an important mechanism for the evolution of new reproductive proteins. However, in most cases, each resulting paralog continues to function within the same sex. To investigate the possibility that seminal fluid proteins arise through duplicates of female reproductive genes that become "co-opted" by males, we screened female reproductive genes in Drosophila melanogaster for cases of duplication in which one of the resulting paralogs produces a protein in males that is transferred to females during mating. We identified a set of three tandemly duplicated genes that encode secreted serine-type endopeptidase homologs, two of which are expressed primarily in the female reproductive tract (RT), whereas the third is expressed specifically in the male RT and encodes a seminal fluid protein. Evolutionary and gene expression analyses across Drosophila species suggest that this family arose from a single-copy gene that was female-specific; after duplication, one paralog evolved male-specific expression. Functional tests of knockdowns of each gene in D. melanogaster show that one female-expressed gene is essential for full fecundity, and both female-expressed genes contribute singly or in combination to a female's propensity to remate. In contrast, knockdown of the male-expressed paralog had no significant effect on female fecundity or remating. These data are consistent with a model in which members of this gene family exert effects on females by acting on a common, female-expressed target. After duplication and male co-option of one paralog, the evolution of the interacting proteins could have resulted in differential strengths or effects of each paralog.

Characterization of a Gene Family Encoding SEA (Sea-urchin Sperm Protein, Enterokinase and Agrin)-Domain Proteins with Lectin-Like and Heme-Binding Properties from Schistosoma japonicum

BackgroundWe previously identified a novel gene family dispersed in the genome of Schistosoma japonicum by retrotransposon-mediated gene duplication mechanism. Although many transcripts were identified, no homolog was readily identifiable from sequence information.Methodology/Principal FindingsHere, we utilized structural homology modeling and biochemical methods to identify remote homologs, and characterized the gene products as SEA (sea-urchin sperm protein, enterokinase and agrin)-domain containing proteins. A common extracellular domain in this family was structurally similar to SEA-domain. SEA-domain is primarily a structural domain, known to assist or regulate binding to glycans. Recombinant proteins from three members of this gene family specifically interacted with glycosaminoglycans with high affinity, with potential implication in ligand acquisition and immune evasion. Similar approach was used to identify a heme-binding site on the SEA-domain. The heme-binding mode showed heme molecule inserted into a hydrophobic pocket, with heme iron putatively coordinated to two histidine axial ligands. Heme-binding properties were confirmed using biochemical assays and UV-visible absorption spectroscopy, which showed high affinity heme-binding (K D = 1.605×10−6 M) and cognate spectroscopic attributes of hexa-coordinated heme iron. The native proteins were oligomers, antigenic, and are localized on adult worm teguments and gastrodermis; major host-parasite interfaces and site for heme detoxification and acquisition.ConclusionsThe results suggest potential role, at least in the nucleation step of heme crystallization (hemozoin formation), and as receptors for heme uptake. Survival strategies exploited by parasites, including heme homeostasis mechanism in hemoparasites, are paramount for successful parasitism. Thus, assessing prospects for application in disease intervention is warranted.

The complex becomes more complex: protein-protein interactions of SnRK1 with DUF581 family proteins provide a framework for cell- and stimulus type-specific SnRK1 signaling in plants

In plants, SNF1-related kinase (SnRK1) responds to the availability of carbohydrates as well as to environmental stresses by down-regulating ATP consuming biosynthetic processes, while stimulating energy-generating catabolic reactions through gene expression and post-transcriptional regulation. The functional SnRK1 complex is a heterotrimer where the catalytic α subunit associates with a regulatory β subunit and an activating γ subunit. Several different metabolites as well as the hormone abscisic acid (ABA) have been shown to modulate SnRK1 activity in a cell- and stimulus-type specific manner. It has been proposed that tissue- or stimulus-specific expression of adapter proteins mediating SnRK1 regulation can at least partly explain the differences observed in SnRK1 signaling. By using yeast two-hybrid and in planta bi-molecular fluorescence complementation assays we were able to demonstrate that proteins containing the domain of unknown function (DUF) 581 could interact with both isoforms of the SnRK1α subunit (AKIN10/11) of Arabidopsis. A structure/function analysis suggests that the DUF581 is a generic SnRK1 interaction module and co-expression with DUF581 proteins in plant cells leads to reallocation of the kinase to specific regions within the nucleus. Yeast two-hybrid analyses suggest that SnRK1 and DUF581 proteins share common interaction partners inside the nucleus. The analysis of available microarray data implies that expression of the 19 members of the DUF581 encoding gene family in Arabidopsis is differentially regulated by hormones and environmental cues, indicating specialized functions of individual family members. We hypothesize that DUF581 proteins could act as mediators conferring tissue- and stimulus-type specific differences in SnRK1 regulation.

Inactivation of aPleurotus ostreatusversatile peroxidase‐encoding gene (mnp2) results in reduced lignin degradation

Lignin biodegradation by white-rot fungi is pivotal to the earth's carbon cycle. Manganese peroxidases (MnPs), the most common extracellular ligninolytic peroxidases produced by white-rot fungi, are considered key in ligninolysis. Pleurotus ostreatus, the oyster mushroom, is a preferential lignin degrader occupying niches rich in lignocellulose such as decaying trees. Here, we provide direct, genetically based proof for the functional significance of MnP to P. ostreatus ligninolytic capacity under conditions mimicking its natural habitat. When grown on a natural lignocellulosic substrate of cotton stalks under solid-state culture conditions, gene and isoenzyme expression profiles of its short MnP and versatile peroxidase (VP)-encoding gene family revealed that mnp2 was predominately expressed. mnp2, encoding the versatile short MnP isoenzyme 2 was disrupted. Inactivation of mnp2 resulted in three interrelated phenotypes, relative to the wild-type strain: (i) reduction of 14% and 36% in lignin mineralization of stalks non-amended and amended with Mn(2+), respectively; (ii) marked reduction of the bioconverted lignocellulose sensitivity to subsequent bacterial hydrolyses; and (iii) decrease in fungal respiration rate. These results may serve as the basis to clarify the roles of the various types of fungal MnPs and VPs in their contribution to white-rot decay of wood and lignocellulose in various ecosystems.

Correction: DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

Correction: DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

Correction: DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

Correction: DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

Human DOR/TP53INP2 displays a unique bifunctional role as a modulator of autophagy and gene transcription. However, the domains or regions of DOR that participate in those functions have not been identified. Here we have performed structure/function analyses of DOR guided by identification of conserved regions in the DOR gene family by phylogenetic reconstructions. We show that DOR is present in metazoan species. Invertebrates harbor only one gene, DOR/Tp53inp2, and in the common ancestor of vertebrates Tp53inp1 may have arisen by gene duplication. In keeping with these data, we show that human TP53INP1 regulates autophagy and that different DOR/TP53INP2 and TP53INP1 proteins display transcriptional activity. The use of molecular evolutionary information has been instrumental to determine the regions that participate in DOR functions. DOR and TP53INP1 proteins share two highly conserved regions (region 1, aa residues 28–42; region 2, 66–112 in human DOR). Mutation of conserved hydrophobic residues in region 1 of DOR (that are part of a nuclear export signal, NES) reduces transcriptional activity, and blocks nuclear exit and autophagic activity under autophagy-activated conditions. We also identify a functional and conserved LC3-interacting motif (LIR) in region 1 of DOR and TP53INP1 proteins. Mutation of conserved acidic residues in region 2 of DOR reduces transcriptional activity, impairs nuclear exit in response to autophagy activation, and disrupts autophagy. Taken together, our data reveal DOR and TP53INP1 as dual regulators of transcription and autophagy, and identify two conserved regions in the DOR family that concentrate multiple functions crucial for autophagy and transcription.

Numbers of genes in the NBS and RLK families vary by more than four-fold within a plant species and are regulated by multiple factors

Many genes exist in the form of families; however, little is known about their size variation, evolution and biology. Here, we present the size variation and evolution of the nucleotide-binding site (NBS)-encoding gene family and receptor-like kinase (RLK) gene family in Oryza, Glycine and Gossypium. The sizes of both families vary by numeral fold, not only among species, surprisingly, also within a species. The size variations of the gene families are shown to correlate with each other, indicating their interactions, and driven by natural selection, artificial selection and genome size variation, but likely not by polyploidization. The numbers of genes in the families in a polyploid species are similar to those of one of its diploid donors, suggesting that polyploidization plays little roles in the expansion of the gene families and that organisms tend not to maintain their ‘surplus’ genes in the course of evolution. Furthermore, it is found that the size variations of both gene families are associated with organisms’ phylogeny, suggesting their roles in speciation and evolution. Since both selection and speciation act on organism’s morphological, physiological and biological variation, our results indicate that the variation of gene family size provides a source of genetic variation and evolution.

Phylogenetic analyses of peanut resistance gene candidates and screening of different genotypes for polymorphic markers

The nucleotide-binding-site-leucine-rich-repeat (NBS–LRR)-encoding gene family has attracted much research interest because approximately 75% of the plant disease resistance genes that have been cloned to date are from this gene family. Here, we describe a collection of peanut NBS–LRR resistance gene candidates (RGCs) isolated from peanut ( Arachis) species by mining Gene Bank data base. NBS–LRR sequences assembled into TIR-NBS-LRR (75.4%) and non-TIR-NBS-LRR (24.6%) subfamilies. Total of 20 distinct clades were identified and showed a high level of sequence divergence within TIR-NBS and non-TIR-NBS subfamilies. Thirty-four primer pairs were designed from these RGC sequences and used for screening different genotypes belonging to wild and cultivated peanuts. Therefore, peanut RGC identified in this study will provide useful tools for developing DNA markers and cloning the genes for resistance to different pathogens in peanut.

Gα encoding gene family of the malaria vector mosquito Anopheles gambiae: Expression analysis and immunolocalization of AGαq and AGαo in female antennae

G_α encoding gene family of the malaria vector mosquito <i>Anopheles gambiae</i>: Expression analysis and immunolocalization of AG_αq and AG_αo in female antennae

Gα encoding gene family of the malaria vector mosquito Anopheles gambiae: Expression analysis and immunolocalization of AGαq and AGαo in female antennae

To initiate a comprehensive investigation of chemosensory signal transduction downstream of odorant receptors, we identified and characterized the complete set of genes that encode G-protein alpha subunits in the genome of the malaria vector mosquito An. gambiae. Data are provided on the tissue-specific expression patterns of 10 corresponding aga-transcripts in adult mosquitoes and pre-imago developmental stages. Specific immunoreactivity in chemosensory hairs of female antennae provides evidence in support of the participation of a subset of AGalphaq isoforms in olfactory signal transduction in this mosquito. In contrast, AGalphao is localized along the flagellar axon bundle but is absent from chemosensory sensilla, which suggests that this G-protein alpha subunit does not participate in olfactory signal transduction.