View source for Kinase Subfamily PKR

__NOTOC__
[[kinase classification|Kinase Classification]]: [[Kinase_Group_Other|Group Other]]: [[Kinase_Family_PEK|Family PEK]]: [[Kinase_Subfamily_PKR|PKR]]

PKR (Protein Kinase R) is a member of the stress-responsive [[Kinase_Family_PEK|PEK]] kinase family, which is activated by double-stranded RNA during viral infection. It phosphorylates eIF2a, resulting in decreased protein translation, hence the alternative name of EIF2AK2. Several other mechanisms are thought to be able to activate PKR, and other substrates and mechanisms of action have been studied.

====Evolution====

====Domain Structure====
PKR genes have a pair of RNA-binding DSRM domains, followed by the kinase domain. Some fish have a variant PKR, called PKZ, which has Z-DNA binding domains instead, probably still used to bind viral nucleic acids <cite>Rothenburg</cite>.

====Classification and Evolution====
PKR is a vertebrate-specific gene. It is the target of several viral escape mechanisms, causing the sequence to be extremely fast-evolving <cite>Elde</cite>. Putative homologs of PKR, lacking the DSRM domains, have been found in excavates, annotated as PKR-like <cite>Manning</cite>, though too evolutionarily distant to be obvious orthologs.

====References====
<biblio>
#Elde pmid=19043403
#Manning pmid=21787419
#Rothenburg pmid=15659550
</biblio>