Hyperactivation of hamster sperm motility by temperature-dependent tyrosine phosphorylation of an 80-kDa protein.

Protein phosphorylation and dephosphorylation are believed to play key roles in regulation of sperm motility. Here we examine the effect of temperature on hamster sperm motility and protein tyrosine phosphorylation status. As in previous work, a decrease from 37 degrees C to 22 degrees C caused loss of hyperactivated motility. We now find that cooling also produces a dephosphorylation of several 48-80-kDa flagellar peptides. A return to 37 degrees C restored hyperactivation but resulted in rephosphorylation of only an 80-kDa protein. Conversely, hyperactivation and phosphorylation of the 80-kDa component were insensitive to incubation temperature for sperm incubated with the protein phosphatase inhibitor, calyculin A, or for sperm demembranated by detergent extraction. These results strongly indicate that the temperature-sensitive tyrosine phosphorylation status of an 80-kDa sperm flagellar peptide explains the sensitivity of hyperactivation to temperature.