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A phyloproteomic characterization of in vitro autophosphorylation in calcium‐dependent protein kinases
Author(s) -
Hegeman Adrian D.,
Rodriguez Miguel,
Han Byung Woo,
Uno Yuichi,
Phillips George N.,
Hrabak Estelle M.,
Cushman John C.,
Harper Jeff F.,
Harmon Alice C.,
Sussman Michael R.
Publication year - 2006
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.200500926
Subject(s) - autophosphorylation , biology , kinase , calmodulin , calcium signaling , protein kinase domain , microbiology and biotechnology , phosphorylation , protein kinase a , arabidopsis , biochemistry , signal transduction , gene , mutant , enzyme
Calcium‐dependent protein kinases (CDPKs) are a novel class of signaling molecules that have been broadly implicated in relaying specific calcium‐mediated responses to biotic and abiotic stress as well as developmental cues in both plants and protists. Calcium‐dependent autophosphorylation has been observed in almost all CDPKs examined, but a physiological role for autophosphorylation has not been demonstrated. To date, only a handful of autophosphorylation sites have been mapped to specific residues within CDPK amino acid sequences. In an attempt to gain further insight into this phenomenon, we have mapped autophosphorylation sites and compared these phosphorylation patterns among multiple CDPK isoforms. From eight CDPKs and two CDPK‐related kinases from Arabidopsis thaliana and Plasmodium falciparum , 31 new autophosphorylation sites were characterized, which in addition to the previously described sites, allowed the identification of five conserved loci. Of the 35 total sites analyzed approximately one‐half were observed in the N‐terminal variable domain. Homology models were generated for the protein kinase and calmodulin‐like domains, each containing two of the five conserved sites, to allow intelligent speculation regarding subsequent lines of investigation.