Non-functional fertility genes in humans: contributory factors in reduced male fertility?
Many of the mammalian sperm surface proteins that have been characterized in recent years have been implicated in sperm--egg interactions and subsequent fertilization. In particular, several members of the MDC protein family, most notably fertilin alpha, fertilin beta and cyritestin (also known as tMDC I), play an important role in sperm--egg interactions in rodents. In light of current data, it is proposed that many of these sperm proteins act co-operatively, and that the concerted effects of several proteins leads to 'maximum fertilizing ability', but that individual proteins are functionally redundant and are therefore not essential. Nevertheless, the co-operative nature of these interactions means that loss of individual proteins might lead to a concomitant reduction in fertilizing ability, a proposal that is supported by our recent finding of non-functional fertilin alpha and tMDC I genes in humans.
Hall
Len
L
Bristol Molecular Reproductive Biology Group, Department of Biochemistry, University of Bristol, School of Medical Sciences, Bristol BS8 1TD, UK.
Frayne
Jan
J