Calexcitin
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Calexcitin is a calcium-binding protein first isolated from the sea snail Hermissenda crassicornis. It is upregulated following Pavlovian conditioning.
Calexcitin has four EF-hand motifs that possess different functions while the fourth one is nonfunctional. Calexcitin has the tendency to regulate K+ channels. In addition, Calexcitin also shows a sign of GTP binding protein in which that binds to Ca2+.
Calexcitin is neuronal-specific and becomes phosphorylated and upregulated in learning of association.
Calexcitin which has four EF-hand motifs. The first three function in the binding metal ions which are from EF-1 to EF-3. EF-1 and EF-2 contain the proclivity into binding with Mg2+ and Ca2+. However, the EF-3 has a tendency into binding with Ca2+. The fourth EF-hand does not function due to the lack of metal-binding residues.
Functions
Calexcitin directly regulate the K+ channels. Due to the fact that "Calexcitin is also a high affinity substrate for protein kinase C. Application of calexcitin to the inner surface of inside-out patches of human fibroblast membranes, in the presence of Ca2+ and the absence of endogenous Ca2+/calmodulin kinase type II or protein kinase C activity, reduced the mean open time and mean open probability of 115 ± 6 pS K+ channels". Also, calexcitin is very great at making the membrane to be more excitable due to "When microinjected into molluscan neurons or rabbit cerebellar Purkinje cell dendrites". In addition, calexcitin acts as a Ca2+ activated signaling molecule in which it plays a role into increasing the cellular excitability. while making it more likely to increase the Ca2+ influx in the membrane. Also, this shows an example of GTP-binding protein that by which binds to Ca2+.
References
 | This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. Please help improve this article by introducing more precise citations. (June 2022) (Learn how and when to remove this message) |
- Nelson, Thomas J.; Cavallaro, Sebastiano; Yi, Chu-Li; McPhie, Donna; Schreurs, Bernard G.; Gusev, Pavel A.; Favit, Antonella; Zohar, Ofer; Kim, Jeongho; Beushausen, Sven; Ascoli, Giorgio; Olds, James; Neve, Rachael; Alkon, Daniel L. (1996). "Calexcitin: A signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability". Proceedings of the National Academy of Sciences. 93 (24): 13808–13813. Bibcode:1996PNAS...9313808N. doi:10.1073/pnas.93.24.13808. PMC 19433. PMID 8943017.
- Nelson, T. J.; Cavallaro, S.; Yi, C. L.; McPhie, D.; Schreurs, B. G.; Gusev, P. A.; Favit, A.; Zohar, O.; Kim, J.; Beushausen, S.; Ascoli, G.; Olds, J.; Neve, R.; Alkon, D. L. (1996). "Calexcitin: A signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability". Proceedings of the National Academy of Sciences of the United States of America. 93 (24): 13808–13813. Bibcode:1996PNAS...9313808N. doi:10.1073/pnas.93.24.13808. PMC 19433. PMID 8943017.
External links
- calexcitin+protein,+C+elegans at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Nelson T, Cavallaro S, Yi C, McPhie D, Schreurs B, Gusev P, Favit A, Zohar O, Kim J, Beushausen S, Ascoli G, Olds J, Neve R, Alkon D (1996). "Calexcitin: a signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability". Proc Natl Acad Sci USA. 93 (24): 13808–13. Bibcode:1996PNAS...9313808N. doi:10.1073/pnas.93.24.13808. PMC 19433. PMID 8943017.
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