calexcitin
{{Short description|Calcium-binding protein}}
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.
EF-hand motifs
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 =
{{inline|date=June 2022}}
- {{cite journal | doi = 10.1073/pnas.93.24.13808 | title = Calexcitin: A signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability | year = 1996 | last1 = Nelson | first1 = Thomas J. | last2 = Cavallaro | first2 = Sebastiano | last3 = Yi | first3 = Chu-Li | last4 = McPhie | first4 = Donna | last5 = Schreurs | first5 = Bernard G. | last6 = Gusev | first6 = Pavel A. | last7 = Favit | first7 = Antonella | last8 = Zohar | first8 = Ofer | last9 = Kim | first9 = Jeongho | last10 = Beushausen | first10 = Sven | last11 = Ascoli | first11 = Giorgio | last12 = Olds | first12 = James | last13 = Neve | first13 = Rachael | last14 = Alkon | first14 = Daniel L. | journal = Proceedings of the National Academy of Sciences | volume = 93 | issue = 24 | pages = 13808–13813 | pmid = 8943017 | bibcode = 1996PNAS...9313808N | doi-access = free | pmc = 19433 }}
- {{cite journal | pmid = 8943017 | year = 1996 | last1 = Nelson | first1 = T. J. | last2 = Cavallaro | first2 = S. | last3 = Yi | first3 = C. L. | last4 = McPhie | first4 = D. | last5 = Schreurs | first5 = B. G. | last6 = Gusev | first6 = P. A. | last7 = Favit | first7 = A. | last8 = Zohar | first8 = O. | last9 = Kim | first9 = J. | last10 = Beushausen | first10 = S. | last11 = Ascoli | first11 = G. | last12 = Olds | first12 = J. | last13 = Neve | first13 = R. | last14 = Alkon | first14 = D. L. | title = Calexcitin: A signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 93 | issue = 24 | pages = 13808–13813 | doi = 10.1073/pnas.93.24.13808 | pmc = 19433 | bibcode = 1996PNAS...9313808N | doi-access = free }}
External links
- {{MeshName|calexcitin+protein,+C+elegans}}
- {{cite journal |vauthors=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 |title=Calexcitin: a signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability |journal=Proc Natl Acad Sci USA |volume=93 |issue=24 |pages=13808–13 |year=1996 |pmid=8943017 |doi=10.1073/pnas.93.24.13808 |pmc=19433|bibcode=1996PNAS...9313808N |doi-access=free }}
{{Calcium-binding proteins}}