1.A.1.10.12
Type 2 Na+ channel, SCN2A or NaV1.2, of 2,005 aas and 24 TMSs. Mutations give rise to epileptic encephalophathy, Ohtahara syndrome (Nakamura et al. 2013). They may also give rise to autism (ASD) (Tavassoli et al. 2014). This protein is orthologous to the rat Na+ channel, TC# 1.A.1.10.1 and very similar to the type 1 Na+ channel (1.A.1.10.7). NaV1.2 has a single pore-forming alpha-subunit and two transmembrane beta-subunits. Expressed primarily in the brain, NaV1.2 is critical for initiation and propagation of action potentials. Milliseconds after the pore opens, sodium influx is terminated by inactivation processes mediated by regulatory proteins including calmodulin (CaM). Both calcium-free (apo) CaM and calcium-saturated CaM bind tightly to an IQ motif in the C-terminal tail of the alpha-subunit. Thermodynamic studies and solution structure (2KXW) of a C-domain fragment of apo 13C,15N- CaM (CaMC) bound to an unlabeled peptide with the sequence of the rat NaV1.2 IQ motif showed that apo CaMC (a) was necessary and sufficient for binding, and (b) bound more favorably than calcium-saturated CaMC. CaMN apparently does not influence apo CaM binding to NaV1.2IQp (Mahling et al. 2017). The phenotypic spectrum of SCN2A-related epilepsy is broad, ranging from benign epilepsy in neonate and infancy to severe epileptic encephalopathy. Oxcarbazepine and valproate are the most effective drugs in epilepsy patients with SCN2A variants. Sodium channel blockers often worsen seizures in patients with seizure onset beyond 1 year of age. Abnormal brain MRI findings and de novo variations are often related to poor prognosis. Most SCN2A variants located in transmembrane regions were related to patients with developmental delay (Zeng et al. 2022). The beta4-subunit and PRRT2 form a push-pull system that finely tunes the membrane expression and function of NaV channels and the intrinsic neuronal excitability (Valente et al. 2022).
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| Accession Number: | Q99250 |
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| Protein Name: | Sodium channel protein type 2 subunit alpha |
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| Length: | 2005 |
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| Molecular Weight: | 227975.00 |
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| Species: | Homo sapiens (Human) [9606] |
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| Number of TMSs: | 20 |
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| Location1 / Topology2 / Orientation3: |
Membrane1 / Multi-pass membrane protein2 |
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| Substrate |
sodium(1+) |
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1: MAQSVLVPPG PDSFRFFTRE SLAAIEQRIA EEKAKRPKQE RKDEDDENGP KPNSDLEAGK
61: SLPFIYGDIP PEMVSVPLED LDPYYINKKT FIVLNKGKAI SRFSATPALY ILTPFNPIRK
121: LAIKILVHSL FNMLIMCTIL TNCVFMTMSN PPDWTKNVEY TFTGIYTFES LIKILARGFC
181: LEDFTFLRDP WNWLDFTVIT FAYVTEFVDL GNVSALRTFR VLRALKTISV IPGLKTIVGA
241: LIQSVKKLSD VMILTVFCLS VFALIGLQLF MGNLRNKCLQ WPPDNSSFEI NITSFFNNSL
301: DGNGTTFNRT VSIFNWDEYI EDKSHFYFLE GQNDALLCGN SSDAGQCPEG YICVKAGRNP
361: NYGYTSFDTF SWAFLSLFRL MTQDFWENLY QLTLRAAGKT YMIFFVLVIF LGSFYLINLI
421: LAVVAMAYEE QNQATLEEAE QKEAEFQQML EQLKKQQEEA QAAAAAASAE SRDFSGAGGI
481: GVFSESSSVA SKLSSKSEKE LKNRRKKKKQ KEQSGEEEKN DRVRKSESED SIRRKGFRFS
541: LEGSRLTYEK RFSSPHQSLL SIRGSLFSPR RNSRASLFSF RGRAKDIGSE NDFADDEHST
601: FEDNDSRRDS LFVPHRHGER RHSNVSQASR ASRVLPILPM NGKMHSAVDC NGVVSLVGGP
661: STLTSAGQLL PEGTTTETEI RKRRSSSYHV SMDLLEDPTS RQRAMSIASI LTNTMEELEE
721: SRQKCPPCWY KFANMCLIWD CCKPWLKVKH LVNLVVMDPF VDLAITICIV LNTLFMAMEH
781: YPMTEQFSSV LSVGNLVFTG IFTAEMFLKI IAMDPYYYFQ EGWNIFDGFI VSLSLMELGL
841: ANVEGLSVLR SFRLLRVFKL AKSWPTLNML IKIIGNSVGA LGNLTLVLAI IVFIFAVVGM
901: QLFGKSYKEC VCKISNDCEL PRWHMHDFFH SFLIVFRVLC GEWIETMWDC MEVAGQTMCL
961: TVFMMVMVIG NLVVLNLFLA LLLSSFSSDN LAATDDDNEM NNLQIAVGRM QKGIDFVKRK
1021: IREFIQKAFV RKQKALDEIK PLEDLNNKKD SCISNHTTIE IGKDLNYLKD GNGTTSGIGS
1081: SVEKYVVDES DYMSFINNPS LTVTVPIAVG ESDFENLNTE EFSSESDMEE SKEKLNATSS
1141: SEGSTVDIGA PAEGEQPEVE PEESLEPEAC FTEDCVRKFK CCQISIEEGK GKLWWNLRKT
1201: CYKIVEHNWF ETFIVFMILL SSGALAFEDI YIEQRKTIKT MLEYADKVFT YIFILEMLLK
1261: WVAYGFQVYF TNAWCWLDFL IVDVSLVSLT ANALGYSELG AIKSLRTLRA LRPLRALSRF
1321: EGMRVVVNAL LGAIPSIMNV LLVCLIFWLI FSIMGVNLFA GKFYHCINYT TGEMFDVSVV
1381: NNYSECKALI ESNQTARWKN VKVNFDNVGL GYLSLLQVAT FKGWMDIMYA AVDSRNVELQ
1441: PKYEDNLYMY LYFVIFIIFG SFFTLNLFIG VIIDNFNQQK KKFGGQDIFM TEEQKKYYNA
1501: MKKLGSKKPQ KPIPRPANKF QGMVFDFVTK QVFDISIMIL ICLNMVTMMV ETDDQSQEMT
1561: NILYWINLVF IVLFTGECVL KLISLRYYYF TIGWNIFDFV VVILSIVGMF LAELIEKYFV
1621: SPTLFRVIRL ARIGRILRLI KGAKGIRTLL FALMMSLPAL FNIGLLLFLV MFIYAIFGMS
1681: NFAYVKREVG IDDMFNFETF GNSMICLFQI TTSAGWDGLL APILNSGPPD CDPDKDHPGS
1741: SVKGDCGNPS VGIFFFVSYI IISFLVVVNM YIAVILENFS VATEESAEPL SEDDFEMFYE
1801: VWEKFDPDAT QFIEFAKLSD FADALDPPLL IAKPNKVQLI AMDLPMVSGD RIHCLDILFA
1861: FTKRVLGESG EMDALRIQME ERFMASNPSK VSYEPITTTL KRKQEEVSAI IIQRAYRRYL
1921: LKQKVKKVSS IYKKDKGKEC DGTPIKEDTL IDKLNENSTP EKTDMTPSTT SPPSYDSVTK
1981: PEKEKFEKDK SEKEDKGKDI RESKK