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closeCould MIFII be a calcium or bicarbonate binding protein?
Posted by lrlevin on 12 Aug 2010 at 16:33 GMT
I realize its effective concentrations of 1-2 µg/ml reveal it is active at nM concentrations, which would be too low to adversely affect the mM Ca2+ or HCO3- concentrations in standard capacitation buffers, but it is unclear how much Ca2+ and/or HCO3- are actually added to the sperm in these experiments. If the levels of these sAC activators are low enough in the control situation, couldn't MIFII simply be chelating sufficient free Ca2+ or HCO3- in the epididymal plasma to prevent sAC activation?
RE: Could MIFII be a calcium or bicarbonate binding protein?
srdungdung replied to lrlevin on 13 Aug 2010 at 10:00 GMT
Firstly, effect of MIF-II on capacitation as well as acrosome reaction is yet to be checked. In this study we have used modified RPS medium to check motility which is devoid of both Ca2+ and HCO3-.
Our preliminary studies showed that Ca2+ (1mM) has no effect on MIF-II activity and vice versa. So, it may be working through some other pathway related to cAMP. We are now investigating the possible mechanism of MIF-II action.
We have not seen the direct effect of bicarbonate on MIF-II. But, as MIF-II is inactive at alkaline pH, so it is likely that MIF-II is not a bicarbonate dependent protein.