The porcine sperm motility inhibitor is identical to beta-microseminoprotein and is a competitive inhibitor of Na+,K(+)-ATPase.
We have isolated a small porcine seminal protein called SMI-1. Our results from peptide sequence, amino acid composition and mass spectral analyses reveal that SMI-1 is identical to porcine beta-microseminoprotein, a protein with unknown function. We also report here that this protein inhibits competitively the activity of Na+,K(+)-ATPase purified from porcine cerebral cortex in a dose-dependent manner. The inhibitory effect could be reversed by the addition of ATP. The half-maximal inhibition was achieved at an inhibitor concentration of 90 microM.
Chao
C F
CF
Institute of Biochemical Sciences, National Taiwan University, Taipei, R.O.C.
Chiou
S T
ST
Jeng
H
H
Chang
W C
WC
D000595:Amino Acid Sequence; D000818:Animals; D004791:Enzyme Inhibitors / Q000737:chemistry*; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D029584:Prostatic Secretory Proteins; D011506:Proteins / Q000737:chemistry*; D012661:Semen / Q000737:chemistry*; D029589:Seminal Plasma Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013094:Spermatozoa / Q000201:enzymology*; D013552:Swine
D004791:Enzyme Inhibitors; D029584:Prostatic Secretory Proteins; D011506:Proteins; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein; D000254:Sodium-Potassium-Exchanging ATPase