3wfn

Structural highlights

Disease

SCN8A_MOUSE Defects in Scn8a are the cause of motor endplate disease (med). Med is a recessive neuromuscular disorder that is characterized by lack of signal transmission at the neuromuscular junction, excess preterminal arborization and degeneration of cerebellar Purkinje cells. It produces early onset progressive paralysis of hind limbs, severe muscle atrophy and juvenile lethality. Defects in Scn8a are the cause of the jolting mutant (medjo), a mild form of motor endplate disease which is characterized by the absence of spontaneous, regular, simple discharges from Purkinje cells. After 3 weeks of age, jolting mice are unsteady and have wide-based gait and a rhythmical tremor of head and neck induced by attempted movement.^{[1] [2]} Defects in Scn8a are a cause of degenerating muscle (dmu). Dmu is an autosomal recessive neuromuscular disorder that is characterized by skeletal and cardiac muscle degeneration. It produces early onset progressive loss of mobility of the hind limbs and subsequent lethality in the first month of life.^{[3] [4]}

Function

CALM1_MOUSE Calmodulin mediates the control of a large number of enzymes, ion channels, aquaporins and other proteins through calcium-binding. Among the enzymes to be stimulated by the calmodulin-calcium complex are a number of protein kinases and phosphatases. Together with CCP110 and centrin, is involved in a genetic pathway that regulates the centrosome cycle and progression through cytokinesis. Is a regulator of voltage-dependent L-type calcium channels. Mediates calcium-dependent inactivation of CACNA1C. Positively regulates calcium-activated potassium channel activity of KCNN2. Forms a potassium channel complex with KCNQ1 and regulates electrophysiological activity of the channel via calcium-binding. Acts as a sensor to modulate the endoplasmic reticulum contacts with other organelles mediated by VMP1:ATP2A2 (By similarity).[UniProtKB:P0DP23]SCN8A_MOUSE Mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient. In macrophages, isoform 5 may participate in the control of podosome and invadopodia formation.^[5]

References

1. ↑ Burgess DL, Kohrman DC, Galt J, Plummer NW, Jones JM, Spear B, Meisler MH. Mutation of a new sodium channel gene, Scn8a, in the mouse mutant 'motor endplate disease'. Nat Genet. 1995 Aug;10(4):461-5. PMID:7670495 doi:10.1038/ng0895-461
2. ↑ Kohrman DC, Smith MR, Goldin AL, Harris J, Meisler MH. A missense mutation in the sodium channel Scn8a is responsible for cerebellar ataxia in the mouse mutant jolting. J Neurosci. 1996 Oct 1;16(19):5993-9. PMID:8815882 doi:10.1523/JNEUROSCI.16-19-05993.1996
3. ↑ De Repentigny Y, Côté PD, Pool M, Bernier G, Girard S, Vidal SM, Kothary R. Pathological and genetic analysis of the degenerating muscle (dmu) mouse: a new allele of Scn8a. Hum Mol Genet. 2001 Aug 15;10(17):1819-27. PMID:11532991 doi:10.1093/hmg/10.17.1819
4. ↑ Kohrman DC, Harris JB, Meisler MH. Mutation detection in the med and medJ alleles of the sodium channel Scn8a. Unusual splicing due to a minor class AT-AC intron. J Biol Chem. 1996 Jul 19;271(29):17576-81. PMID:8663325 doi:10.1074/jbc.271.29.17576
5. ↑ Carrithers MD, Chatterjee G, Carrithers LM, Offoha R, Iheagwara U, Rahner C, Graham M, Waxman SG. Regulation of podosome formation in macrophages by a splice variant of the sodium channel SCN8A. J Biol Chem. 2009 Mar 20;284(12):8114-26. PMID:19136557 doi:10.1074/jbc.M801892200