Protein phosphatase

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:

1. PP1
2. PP2A
3. PP2B (aka calcineurine?)
4. 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