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1.A.1.3.5
Sperm Slo3 high conductance K+ channel, activated by voltage and intracellular alkalinization. In sperm, it gives rise to pH-dependent outwardly rectifying K+ currents. (required for the ensuing acrosome reaction; activated by phosphatidylinositol 4,5-bisphosphate (PIP(2)) (Tang et al., 2010). The Slo3 cytosolic module confers pH-dependent regulation whereas the Slo1 (TC# 1.A.1.3.2)  cytosolic module confers Ca2+-dependent regulation (Xia et al. 2004). When mammalian sperm are released in the female reproductive tract, they are incapable of fertilizing the oocyte. They need a prolonged exposure to the alkaline medium of the female genital tract before their flagellum gets hyperactivated and the acrosome reaction can take place, allowing the sperm to interact with the oocyte (de Prelle et al. 2022). Ionic fluxes across the sperm membrane are involved in two essential aspects of capacitation: the increase in intracellular pH and membrane hyperpolarization. The SLO3 potassium channel and the sNHE sodium-proton exchanger are necessary for the capacitation process to occur. As the SLO3 channel is activated by an increase in intracellular pH and sNHE is activated by hyperpolarization, they act together as a positive feedback system (de Prelle et al. 2022).

Accession Number:O54982
Protein Name:Potassium channel subfamily U member 1
Length:1121
Molecular Weight:126870.00
Species:Mus musculus (Mouse) [10090]
Number of TMSs:6
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate potassium(1+)

Cross database links:

Entrez Gene ID: 16532   
Pfam: PF03493    PF00520   
KEGG: mmu:16532   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0005488 F:binding
GO:0015269 F:calcium-activated potassium channel activity
GO:0003824 F:catalytic activity
GO:0005244 F:voltage-gated ion channel activity

References (6)

[1] “Slo3, a novel pH-sensitive K+ channel from mammalian spermatocytes.”  Schreiber M.et.al.   9452476
[2] “Intracellular Mg(2+) enhances the function of BK-type Ca(2+)-activated K(+) channels.”  Shi J.et.al.   11696614
[3] “Gating and conductance properties of BK channels are modulated by the S9-S10 tail domain of the alpha subunit. A study of mSlo1 and mSlo3 wild-type and chimeric channels.”  Moss B.L.et.al.   11723163
[4] “Ligand-dependent activation of Slo family channels is defined by interchangeable cytosolic domains.”  Xia X.-M.et.al.   15201331
[5] “Slo3 K+ channels: voltage and pH dependence of macroscopic currents.”  Zhang X.et.al.   16940555
[6] “pH-regulated Slo3 K+ channels: properties of unitary currents.”  Zhang X.et.al.   16940554

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FASTA formatted sequence 
1:	MSQTLLDSLN QKELTETSCT IEIQAAFILS SLATFFGGLI ILFLFRIALK SSRSWKYVKG 
61:	PRGLLELFSS RRIEANPLRK LYFHGVFRQR IEMLLSAQTV VGQVLVILVF VLSIGSLVIY 
121:	FINSMDPVRR CSSYEDKIVH GDLSFNAFFS FYFGLRFWAA EDKIKFWLEM NSIVDIFTIP 
181:	PTFISYYLKS NWLGLRFLRA LRLLELPKIL QILQVIKTSN SVKLSKLLSI VISTWFTAAG 
241:	FLHLVENSGD PWLNGRNSQT MSYFESIYLV TATMSTVGFG DVVAKTSLGR IFIVFFTLGS 
301:	LILFANYIPE MVELFSTRKK YTKPYEAVKG KKFIVVCGNI TVDSVTAFLR NFLHWKSGEI 
361:	NIEIVFLGET LPCLELETLL KCHTSCTNFV CGTALKFEDL KRVAVENSEA CLILANHFCS 
421:	DLHDEDNSNI MRVLSIKNYY PQTRVIIQIL QSQNKVFLSK IPNWDWSAGD NILCFAELKL 
481:	GFIAQGCLVP GLCTFLTTLF IEQNQKVFPK HPWQKHFLNG LKNKILTQRL SNDFVGMTFP 
541:	QVSRLCFVKL NLMLIAIQHK PFFHSCCTLI LNPSSQVRLN KDTLGFFIAD SSKAVKRAFF 
601:	YCSNCHSDVC NPELIGKCNC KIKSRQQLIA PTIMVMKSSL TDFTTSSHIH ASMSTEIHTC 
661:	FSREQPSLIT ITTNRPTTND TVDDTDMLDS SGMFHWCRAM PLDKVVLKRS EKAKHEFQNH 
721:	IVVCVFGDAQ CTLVGLRNFV MPLRASNYTR QELKDIVFIG SLEYFQREWR FLRNFPKIHI 
781:	MPGSALYMGD LIAVNVEQCS MCVILATPYK ALSSQILVDT EAIMATLNIQ SLRITSPTPG 
841:	SSKSEVKPSS AFDSKERKQR YKQIPILTEL KNPSNIHFIE QMGGLDGMLK GTSLHLSTSF 
901:	STGAVFSDTF LDSLLATSFY NYHVVELLQM LVTGGISSEM EHYLVKEKPY KTTDDYEAIK 
961:	SGRTRCKLGL LSLDQTVLSG INPRKTFGQL FCGSLDNFGI LCVGLYRMID EEEPSQEHKR 
1021:	FVITRPSNEC HLLPSDLVFC AIPFNTTCGK SDSSPSIQAQ NNSTNATTPL AQGSNFFDSH 
1081:	HADESHDLYP VDDTGERWSQ HHHSRVYPLD TLDASDIVQE K