Purification and characterization of a human follicular fluid lipid transfer protein that stimulates human sperm capacitation

S. E. Ravnik, P. W. Zarutskie, C. H. Muller

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Identification of the mechanisms responsible for sperm capacitation has been an active area of research for nearly four decades. Changes in the lipid composition of the sperm membrane is one of the biochemical events that occurs during sperm capacitation. We have been studying physiological effectors of some of these changes and have identified lipid transfer activity in fractions of human follicular fluid that stimulates sperm penetration of zona-free hamster oocytes. We report here the purification of a lipid transfer protein by sequential chromatography from human follicular fluid. This protein was purified greater than 20 000-fold for lipid transfer activity and greater than 28 000-fold for sperm penetration-inducing activity. This 64 000 molecular weight protein has a pI of approximately 5.0 and shares physicochemical characteristics with the plasma lipid transfer protein, LTP-I. Antibodies to LTP-I also recognize this protein and depletion of LTP-I from human follicular fluid by immunoaffinity chromatography renders the follicular fluid incapable of stimulating sperm penetration. We conclude that purified LTP-I is able to stimulate human sperm capacitation and that LTP-I is a molecule responsible for this stimulation in follicular fluid.

Original languageEnglish (US)
Pages (from-to)1126-1133
Number of pages8
JournalBiology of reproduction
Volume47
Issue number6
DOIs
StatePublished - 1992

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology

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