Pleckstrins are a family of proteins found in platelets[1] and other cells. The name derives from platelet and leukocyte C kinase substrate and the KSTR string of amino acids. The prototype protein, now called pleckstrin-1, was first identified in 1979 as the major substrate of protein kinase C in platelets.[2] The homolog pleckstrin-2 is more widely expressed in tissues.[3]
The pleckstrin homology domain (PH domain) was named after pleckstrin-1.[2]
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Sequence and structure
Both pleckstrin-1 and pleckstrin-2 contain two pleckstrin homology domains, separated by a central dishevelled-Egl10-pleckstrin (DEP) domain. Pleckstrin-1 is phosphorylated by protein kinase C on three serine and threonine residues located between the first pleckstrin homology domain and the DEP domain;[2] pleckstrin-2 is not a substrate for protein kinase C.[2][4] The two proteins share 65% sequence homology [2] and have a size of about 47 kilodaltons.[5]
As of 2024, no high-resolution three-dimensional structure has been solved for full-length pleckstrin, but the structures of the individual domains of both pleckstrin-1 and -2 have been published.[2]
Functions
Pleckstrins are involved in rearranging the actin cytoskeleton in such processes as platelet activation, erythropoeisis, and cell spreading by extension of filopodia and lamellipodia.[3] Pleckstrin-1 is believed to become activated by protein kinase C phosphorylation, which results in binding of the membrane lipid phosphatidylinositol 3,4-bisphosphate.[2] Interactions with integrins and the Rac GTPase then lead to reorganization of the actin cytoskeleton.[3] Pleckstrin-2 also binds to inositol phospholipids, but interacts directly with F-actin, unlike pleckstrin-1.[3] Since pleckstrin-2 is expressed in a wider variety of cell types, its biological roles are more diverse than those of pleckstrin-1.
Pleckstrin-1 is a key protein in the membrane remodelling processes that occur during platelet activation.[2] It also occurs in immune cells such as macrophages and neutrophils,[2][3] where it is involved in formation of phagosomes and the secretion of proinflammatory cytokines.[3]
Pleckstrin-2 has roles in cell spreading, inflammation, erythropoeisis, and tumorigenesis. In lymphocytes, it is involved in PI3 kinase-mediated immune synapse formation. Pleckstrin-2 also mediates cytoskeletal changes involved in proliferation of erythroblasts early in erythropoeisis. It is also believed to be crucial in the epithelial-to-mesenchymal transition in tumor metastasis, and pleckstrin-2 is known to be overexpressed in a variety of cancers.[3]
References
- ^ Harlan JE, Hajduk PJ, Yoon HS, Fesik SW (September 1994). "Pleckstrin homology domains bind to phosphatidylinositol-4,5-bisphosphate". Nature. 371 (6493): 168–170. Bibcode:1994Natur.371..168H. doi:10.1038/371168a0. hdl:10356/94313. PMID 8072546. S2CID 4321763.
- ^ a b c d e f g h i Edlich C, Stier G, Simon B, Sattler M, Muhle-Goll C (February 2005). "Structure and phosphatidylinositol-(3,4)-bisphosphate binding of the C-terminal PH domain of human pleckstrin". Structure. 13 (2): 277–286. doi:10.1016/j.str.2004.11.012. PMID 15698571.
- ^ a b c d e f g Wang G, Zhou Q, Xu Y, Zhao B (2021). "Emerging Roles of Pleckstrin-2 Beyond Cell Spreading". Frontiers in Cell and Developmental Biology. 9: 768238. doi:10.3389/fcell.2021.768238. PMC 8637889. PMID 34869363.
- ^ Hu MH, Bauman EM, Roll RL, Yeilding N, Abrams CS (July 30, 1999). "Pleckstrin 2, a widely expressed paralog of pleckstrin involved in actin rearrangement". J Biol Chem. 274 (31): 21515–21518. doi:10.1074/jbc.274.31.21515. PMID 10419454.
- ^ "PLEK - Pleckstrin - Homo sapiens (Human)". Uniprot. EMBI-EBL. Retrieved 18 Mar 2024.
External links
- pleckstrin at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
This page was last edited on 8 April 2024, at 21:57