Purification and characterization of a motility initiating protein from caprine epididymal plasma.
Numerous reports have appeared on the occurrence of undefined protein factors in male reproductive fluids that promote motility of mature sperm and initiate forward motility in the immature (immotile) caput-epididymal sperm. This study reports for the first time purification to apparent homogeneity of a motility initiating protein (MIP) from epididymal plasma and its characterization using the caprine sperm model. It is a 125 kDa (approximately) dimeric protein made up of two subunits: 70 and 54 kDa. MIP is an acidic protein with an isoelectric point of 4.75. The motility protein at 30 microg/ml (240 nM) level showed nearly maximal motility-promoting activity. MIP is heat stable and it is maximally active at pH 8. It is a glycoprotein that binds with high affinity to concanavalin A and it contains mannose, galactose, and N-acetyl glucosamine approximately in the ratios of 6:1:6. It is sensitive to the actions of alpha-mannosidase and beta-N-acetylglucoseaminidase thereby demonstrating that the sugar side chain of the glycoprotein is essential for its biological activity. Epididymal plasma is its richest source. It is also capable of enhancing forward motility of mature cauda-sperm. Its antibody markedly inhibits sperm motility. MIP antibody is highly immunospecific and it recognizes both the subunits. MIP causes significant increase of the intrasperm level of cyclic AMP. MIP: the physiological motility-activating protein has potential for use as a contraceptive vaccine and for solving some of the problems of human infertility and animal breeding.
Indian Institute of Chemical Biology, Kolkata, India.
Bijay Shankar
BS
Jaiswal
Kaushik
K
Das
Sudipta
S
Saha
Sandhya Rekha
SR
Dungdung
Gopal C
GC
Majumder
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D000918:Antibody Specificity / Q000187:drug effects; D015153:Blotting, Western; D002846:Chromatography, Affinity; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D000242:Cyclic AMP / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism*; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006041:Goats / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007525:Isoelectric Focusing; D008297:Male; D020409:Molecular Motor Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D009928:Organ Specificity / Q000187:drug effects; D012015:Reference Standards; D012661:Semen / Q000378:metabolism*; D013081:Sperm Motility / Q000187:drug effects
D000906:Antibodies; D006023:Glycoproteins; D020409:Molecular Motor Proteins; D000242:Cyclic AMP; D006026:Glycoside Hydrolases