Protein phosphatase?s are
enzymes that can remove
phosphates that have been attached to
amino acid residues of proteins by
protein kinases. The phosphates are important in [singal transduction]
? by regulating the proteins they are attached to. To alter the regulation, the phosphate has to be removed again. This occurs on its own by hydrolyzation
?, or is mediated by protein phosphatases.
Serine?/Threonine?-specific protein phosphatases
Serine and threonine phosphates are quite stable under physiological conditions, so a phosphatase has to remove the phosphate to remove the regulation. There a four known groups:
- PP1
- PP2A
- PP2B (aka calcineurine?)
- PP2C
The first three have a [sequence homology]
? in the
catalytic domain, but differ in substrate specifity.
Ser/Thr
?-specific protein phosphatases are regulated by localization within the
cell, and by specific inhibitor
? proteins.
Tyrosine-specific protein phosphatases