Table 1. Identified CatSper subunits and their physiological significance in male reproduction

Subunit	Topology	First identification	Knockout mouse	Human patients
CatSper1	6 TM with VSD	EST library screening	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	Male fertility: infertileSpermatogenesis: impairedMotility: reduced
CatSper2	6 TM with VSD	Signaling peptide trapping	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	Male fertility: infertileSpermatogenesis: impairedMotility: reduced
CatSper3	6 TM with VSD	Sequence comparison	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	ND
CatSper4	6 TM with VSD	Sequence comparison	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	ND
CatSperβ	1 TM	CatSper1 interactome	ND	ND
CatSperγ	1 TM	CatSper1 interactome	ND	ND
CatSperδ	1 TM	CatSper1 interactome	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	ND
CatSperε	1 TM	Sequence comparison	ND	Male fertility: infertileSpermatogenesis: normalMotility: normal
CatSperζ	Non-TM	CatSper1 interactome	Male fertility: SubfertileSpermatogenesis: normalHyperactivation: defective	ND
EFCAB9	Non-TM	Sperm proteome comparison	Male fertility: SubfertileSpermatogenesis: normalHyperactivation: defective	ND
CatSperτ	Non-TM	Sperm proteome comparison	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	Male fertility: infertilespermatogenesis: NDMotility: ND
CatSperη	3 TM	Atomic structure analysis	ND	ND
CatSperθ	2 TM	Atomic structure analysis	Male fertility: infertileSpermatogenesis: normalHyperactivation: defective	ND
Slco6C1	12 TM	Atomic structure analysis	ND	ND

TM, transmembrane; VSD, voltage-sensing domain; EST, expression sequencing tag; ND, non-determined.