Isolation and partial characterization of an ion channel protein from human sperm membranes.
Human sperm cells were fractionated and plasma membrane proteins were separated by molecular gel sieving chromatography (Sephacryl S-200 followed by HPLC). A pore-forming protein was extracted from sperm cell membranes. The partially purified protein migrated with Mr 100,000-110,000, as determined by molecular sieving gel chromatography, and with a Mr 90,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. The channel activity was also extracted with Triton X-114, suggesting a hydrophobic nature for this protein. This protein was incorporated into planar lipid bilayers, resulting in the formation of voltage-dependent ion channels. Single channel fluctuations of 130 pS/unit in 0.1 M NaCl were resolved; however, channels preferentially aggregated in triplets having an open state life-time that persisted for several seconds. The channels studied here were more selective for monovalent cations than anions, but also showed some permeability to anions and larger electrolytes, suggesting a large functional pore diameter. The role of this sperm channel in normal sperm physiology and/or fertilization is presently unclear.
D002463:Cell Membrane Permeability; D002850:Chromatography, Gel; D006801:Humans; D007473:Ion Channels / Q000032:analysis*; D008051:Lipid Bilayers; D008297:Male; D008565:Membrane Proteins / Q000302:isolation & purification*; D013094:Spermatozoa / Q000032:analysis*
D007473:Ion Channels; D008051:Lipid Bilayers; D008565:Membrane Proteins