Nomenclature	CatSper1	CatSper2	CatSper3	CatSper4
HGNC, UniProt	CATSPER1, Q8NEC5	CATSPER2, Q96P56	CATSPER3, Q86XQ3	CATSPER4, Q7RTX7
Activators	CatSper1 is constitutively active, weakly facilitated by membrane depolarisation, strongly augmented by intracellular alkalinisation. In human, but not mouse, spermatozoa progesterone (EC50 ∼ 8 nM) also potentiates the CatSper current (ICatSper).	–	–	–
Channel Blockers (IC50)	NNC55-0396 (2x10-6 – 1x10-5 M), ruthenium red (1x10-5 M), HC056456 (2x10-5 M), mibefradil (3x10-5 M), Cd2+ (2x10-4 M), Ni2+ (3x10-4 M)	–	–	–
Functional characteristics	Calcium selective ion channel (Ba2+>Ca2+>>Mg2+>>Na+); quasilinear monovalent cation current in the absence of extracellular divalent cations; alkalinization shifts the voltage-dependence of activation towards negative potentials [V½ @ pH 6.0 = +87 mV (mouse); V½ @ pH 7.5 = +11mV (mouse) or pH 7.4 = +85 mV (human)]	Required for ICatSper	Required for ICatSper	Required for ICatSper