Potassium Channel Subfamily U, Member 1 (KCNU1)

Although this channel is structurally related to the calcium-activated potassium channels, it cannot be classified as such since it is activated by high intracellular pH and relatively insensitive to changes in calcium concentrations.

KCNU1 may encode a large-conductance potassium channel (dubbed KSper) activated by both voltage and internal alkalinization, recorded from mature sperm. This channel is thought to underlie a pH-triggered membrane hyperpolarization observed during the process of sperm capacitation, as sperm encounter the alkaline environment near the ovum in the female reproductive tract. Normal capacitation is required for sperm to become fully competent for fertilization.In CATSPER1-deficient sperm, the CATSPERG protein, but not a K+ channel protein KCNU1, is also lost.