Journal
MOLECULAR REPRODUCTION AND DEVELOPMENT
Volume 66, Issue 1, Pages 8-16Publisher
WILEY
DOI: 10.1002/mrd.10327
Keywords
COX; mitochondria; cDNA; energy; evolution
Funding
- NIGMS NIH HHS [GM48517] Funding Source: Medline
Ask authors/readers for more resources
Sperm motility is highly dependent on aerobic energy metabolism, of which the apparent rate-limiting step of the mitochondrial respiratory chain is catalyzed by cytochrome c oxidase (COX). COX is the only electron transport chain complex to display isoforms, consistent with its suggested rate-limiting role. Isoforms were previously described for four of the 13 subunits. We now report the discovery that COX subunit VIb displays a testes-specific isoform in human, bull, rat, and mouse (COX VIb-2). Analysis of a variety of rat and mouse tissues, including ovaries, demonstrates exclusive expression of VIb-2 in testes, whereas VIb-1 transcripts are absent in rodent testes, even at early developmental stages. In contrast, both isoforms are transcribed in human testes. In situ hybridizations with human, rat, and mouse testes sections reveal VIb-2 transcripts in all testicular cell types. Within the seminiferous tubules, VIb-1 shows stronger signals in the periphery than in the lumen. Previously, cytochrome c was the only component of the mitochondrial respiratory chain known to express a testes-specific isoform in mammals. COX subunit VIb connects the two COX monomers into the physiological dimeric form, and is the only COX subunit that, like cytochrome c, is solely located in the inter-membrane space. Significant differences between the isoform sequences, in particular changes in charged amino acids, suggest interactions with cytochrome c and sperm-specific energy requirements. (C) 2003 Wiley-Liss, Inc.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available