Bicarbonate Sensing by Sperm

Science's STKE  01 Aug 2000:
Vol. 2000, Issue 43, pp. tw7
DOI: 10.1126/stke.2000.43.tw7

When exposed to prostatic and vaginal fluids, ejaculated mammalian sperm undergo increased motility, capacitation, and the acrosome reaction. These processes can be triggered by bicarbonate ions and depend on increased production of cAMP (cyclic adenosine 3',5'-monophosphate). Chen et al. now report that the bicarbonate sensor appears to be the recently cloned soluble adenylyl cyclase (sAC), which is activated in the presence of bicarbonate to produce more cAMP. The mammalian sAC protein is closely related to adenylyl cyclases from cyanobacteria that are also stimulated by bicarbonate ions. Thus, regulation of cAMP signaling through bicarbonate-sensitive sACs appears to be an evolutionarily conserved mechanism that could also function in other animal tissues where sAC is present and bicarbonate concentrations are regulated.

Chen, Y., Cann, M.J., Litvin, T.N., Iourgenko, V., Sinclair, M.L., Levin, L.R., and Buck, J. (2000) Soluble adenylyl cyclase as an evolutionarily conserved bicarbonate sensor. Science 289: 625-628. [Abstract] [Full Text]