Two Novel Odorant Receptor Families Expressed in Spermatids Undergo 5′-Splicing

Loren D Walensky,Martial Ruat,Robert E Bakin,Seth Blackshaw,Gabriele V Ronnett,Solomon H Snyder

doi:10.1074/jbc.273.16.9378

Loren D Walensky, Martial Ruat + Show 4 more

Open Access

https://doi.org/10.1074/jbc.273.16.9378

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Abstract

We report the identification of two novel families of odorant receptor (OdR)-like proteins, termed spermatid chemoreceptors (SCRs), in rat spermatids of the testis. The full-length genomic clones encode seven transmembrane domain receptors that share 35-40% identity with certain OdRs and are among the most divergent members of the OdR superfamily based on phylogenetic analysis. RNase protection assays and in situ hybridization studies confirmed the expression of SCRs in spermatids, the post-meiotic, differentiating cell population in the testis. SCR transcripts were undetectable in the prepubertal testis but were readily identified in spermatids of sexually maturing and mature testis. Rapid amplification of cDNA end-polymerase chain reaction and genomic clone sequencing led to the discovery that SCRs are spliced upstream of their presumptive starting methionines. 5'-Splicing of OdRs may regulate the expression of functional chemoreceptors.

Highlights

In an effort to understand the molecular basis of olfaction, Buck and Axel [1] cloned a family of putative odorant receptors (OdRs)1 predicted to contain up to 1000 distinct gene products [2]
Two Novel Spermatid Chemoreceptor (SCR) Families Are Identified in Purified Round Spermatids—In a search for OdR-like proteins that may serve functional roles in reproduction, we reasoned that the post-meiotic and actively differentiating cells of the testis would be most likely to express chemoreceptors physiologically relevant to mature spermatozoa
The 520-bp product corresponded in size to the band generated from PCR using the control template F2, an originally cloned Buck and Axel OdR

Summary

Introduction

In an effort to understand the molecular basis of olfaction, Buck and Axel [1] cloned a family of putative odorant receptors (OdRs)1 predicted to contain up to 1000 distinct gene products [2]. RACE-PCR and sequencing of genomic clones led to the discovery that SCRs undergo 5Ј-splicing, which may regulate receptor expression during spermatogenesis.

Results

Conclusion