The gene for the human tMDC I sperm surface protein is non-functional: implications for its proposed role in mammalian sperm-egg recognition.
The sperm surface antigen tMDC I (also known as cyritestin) has been proposed to play a role in sperm-egg binding in the mouse via an interaction between its disintegrin-like domain and an integrin receptor on the oolemma plasma membrane. Here we report the cloning and sequence of human tMDC I transcripts and show that they are non-functional, owing to the presence of a variety of deletions, insertions and in-frame termination codons. The absence of a tMDC I protein is further supported by the lack of immunoreactivity on Western blots of human testis and sperm extracts probed with macaque (Macaca fascicularis) and human anti-tMDC I antisera.
Department of Biochemistry, University of Bristol, School of Medical Sciences, Bristol BS8 1TD, U.K.
J
J
Frayne
L
L
Hall
D051722:ADAM Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005260:Female; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013084:Sperm-Ovum Interactions / Q000235:genetics / Q000502:physiology*; D013094:Spermatozoa / Q000201:enzymology / Q000502:physiology*; D013737:Testis / Q000201:enzymology / Q000502:physiology; D014158:Transcription, Genetic
D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D051722:ADAM Proteins; C499566:ADAM3A protein, human; C485429:Adam3 protein, mouse; D008666:Metalloendopeptidases