Abstract
We found that a rat testis cDNA library contained two types of proenkephalin cDNA, corresponding to somatic and germ cell-specific transcripts. The somatic form is identical in primary sequence to previously characterized transcripts from rat brain and heart. The longer germ cell-specific cDNA contains a novel 5' terminus derived from the somatic intron A. We found that germ cell-specific transcripts translate in vitro with significantly lower efficiency than do somatic-type transcripts. Deletion analysis indicated that translational inefficiency is mediated primarily by the presence of four upstream AUG codons followed by short open reading frames within the leader sequence. Secondary structure in the form of a stem-and-loop upstream of the initiator codon for proenkephalin was found to have a slightly inhibitory effect on translation. These results, coupled with the very low abundance of the somatic transcript, provide a possible explanation for the low levels of opioid peptides found in adult rat testis in spite of the abundant quantity of germ cell-specific proenkephalin transcript.
Highlights
We found that a rattestis cDNA library contained two proenkephalin mRNA[13].Sequence analysisof proenkephalin types of proenkephalincDNA, corresponding to somaticcDNA from the testis has revealed that the germ cell-derived and germ cell-specific transcripts.The somatic form is transcript contains a novel5”terminalregion in which the identical in primary sequence to previously character- somatic exon I sequence is replaced witha portion of the first ized transcripts from rat brain and heart
Deletionanalysisindicatedthattranslationalineffiservationsuggests that either proenkephalinmRNAisnot ciency is mediatedprimarilybythepresenceoffour translated efficiently or there is a rapid turnover of the pepupstream AUG codons followed by short open reading tides
That may be exist for testicular proenkephalin mRNA, waenalyzed the leader sequencesof two distinct clones, assessethdeir translatability in in vitro translation systems, andthen deterProenkephalin is onoef three distinct protein precursotrhsat mined the effects of deletion mutagenesis of specific regions i n are proteolytically processed to yield the various members of the leader sequence on translation. the opioid peptide family
Summary
We found that a rattestis cDNA library contained two proenkephalin mRNA[13].Sequence analysisof proenkephalin types of proenkephalincDNA, corresponding to somaticcDNA from the testis has revealed that the germ cell-derived and germ cell-specific transcripts.The somatic form is transcript contains a novel5”terminalregion in which the identical in primary sequence to previously character- somatic exon I sequence is replaced witha portion of the first ized transcripts from rat brain and heart.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
