精子尾部离子通道KSper和CatSper的结构与功能

The Structure and Function of Ion Channels KSper and CatSper in Sperm Tail

钾离子通道KSper和钙离子通道CatSper是精子尾部的两种离子通道,对精子运动、精子超激活和受精功能起着重要作用,受到pH值、膜电位、环腺苷酸类似物等生理刺激物的调控。KSper由主亚基Slo3和辅助亚基LRRC52、KCNMB组成,介导成熟精子所产生的p H值依赖性钾电流(IKSper),调控与细胞膜电位有关的信号通路,从而影响雄性生育功能。CatSper蛋白只表达于精子尾部主段,由4个α亚基(CatSper1~4)和5个辅助亚基β、γ、δ、ε和ζ构成。CatSper蛋白通过调控精子尾部蛋白酪氨酸磷酸化,维持精子的超激活运动。本文综述精子尾部KSper和CatSper这两种离子通道的分子结构、特异性的表达模式和生理功能。

Sperm-specific potassium channel, KSper, and sperm-specific calcium channel, CatSper, are the most important specific ion channels on the spermatozoa, which play a key role in the sperm motility,hyperactivation and fertilization. They are regulated by physiological stimuli, such as pH, membrane potential and cyclic adenosine analogues. The KSper protein expressed on testicles and sperm is composed of the main subunit Slo3 and auxiliary subunit LRRC52. It mediates the p H-dependent K+current(IKSper) produced by mature sperm and regulates the signal transduction process associated with membrane potential, thus influencing male fertility.The CatSper protein expressed exclusively on the principal piece of the sperm tail is composed of CatSper1-4 subunits and 5 auxiliary units, β, γ, δ, ε and ζ. It participates in the spatiotemporal regulation of protein tyrosinephosphorylation, thus maintaining sperm hyperactivation. Three aspects of Ksper and CatSper, molecular structures,modes of expressions and physiological functions, are summarized in this review.