K+ channel subfamily U member 1; Ca+2-activated K+ channel subunit alpha-3; Ca+2-activated K+ channel, subfamily M subunit alpha-3; Slowpoke homolog 3; KCa5 (KCNU1, KCNMA3, KCNMC1, SLO3)

^[1]

Function

testis-specific K+ channel
activated by both intracellular pH & membrane voltage that mediates export of K+
may be involved in sperm capacitation &/or the acrosome reaction, essential steps in fertilization where changes in both intracellular pH & membrane potential are known to occur
in contrast to KCNMA1/SLO1, it is not activated by Ca+2 or Mg+2

homotetramer
constitutes Ca+2-activated K+ channel (putative)
the S4 segment, which is characterized by a series of positively charged amino acids at every 3rd position, is part of the voltage-sensor (putative)
the pore-forming domain (also referred as P region) is imbedded into the membrane, & forms the selectivity filter of the pore; it contains the signature sequence of K+ channels that displays selectivity to K+ (putative)
the RCK N-terminal domain mediates the homotetramerization, thereby promoting assembly of monomers into functional K+ channel (putative)
the C-terminal cytosolic region confers the pH-dependence
belongs to the K+ channel family
contains 1 RCK N-terminal domain

membrane

testis-specific