Structure and function of epididymal protein cysteine-rich secretory protein-1.
Cysteine-rich secretory protein-1 (CRISP-1) is a glycoprotein secreted by the epididymal epithelium. It is a member of a large family of proteins characterized by two conserved domains and a set of 16 conserved cysteine residues. In mammals, CRISP-1 inhibits sperm-egg fusion and can suppress sperm capacitation. The molecular mechanism of action of the mammalian CRISP proteins remains unknown, but certain non-mammalian CRISP proteins can block ion channels. In the rat, CRISP-1 comprises two forms referred to as Proteins D and E. Recent work in our laboratory demonstrates that the D form of CRISP-1 associates transiently with the sperm surface, whereas the E form binds tightly. When the spermatozoa are washed, the E form of CRISP-1 persists on the sperm surface after all D form has dissociated. Cross-linking studies demonstrate different protein-protein interaction patterns for D and E, although no binding partners for either protein have yet been identified. Mass spectrometric analyses revealed a potential post-translational modification on the E form that is not present on the D form. This is the only discernable difference between Proteins D and E, and presumably is responsible for the difference in behavior of these two forms of rat CRISP-1. These studies demonstrate that the more abundant D form interacts with spermatozoa transiently, possibly with a specific receptor on the sperm surface, consistent with a capacitation-suppressing function during sperm transit and storage in the epididymis, and also confirm a tightly bound population of the E form that could act in the female reproductive tract.
Roberts
Kenneth P
KP
Department of Urologic Surgery, University of Minnesota, MMC 394, 420 Delaware Street SE, Minneapolis, MN 55455, USA. rober040@umn.edu
Johnston
Daniel S
DS
Nolan
Michael A
MA
Wooters
Joseph L
JL
Waxmonsky
Nicole C
NC
Piehl
Laura B
LB
Ensrud-Bowlin
Kathy M
KM
Hamilton
David W
DW
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D006801:Humans; D008297:Male; D008322:Mammals; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D051381:Rats; D013094:Spermatozoa / Q000502:physiology*
C103538:CRISP1 protein, human; D008562:Membrane Glycoproteins