Publication Abstract from PubMed
A phosphorylation-initiated mechanism of local protein refolding activates yeast glycogen phosphorylase (GP). Refolding of the phosphorylated amino-terminus was shown to create a hydrophobic cluster that wedges into the subunit interface of the enzyme to trigger activation. The phosphorylated threonine is buried in the allosteric site. The mechanism implicates glucose 6-phosphate, the allosteric inhibitor, in facilitating dephosphorylation by dislodging the buried covalent phosphate through binding competition. Thus, protein phosphorylation-dephosphorylation may also be controlled through regulation of the accessibility of the phosphorylation site to kinases and phosphatases. In mammalian glycogen phosphorylase, phosphorylation occurs at a distinct locus. The corresponding allosteric site binds a ligand activator, adenosine monophosphate, which triggers activation by a mechanism analogous to that of phosphorylation in the yeast enzyme.
A protein phosphorylation switch at the conserved allosteric site in GP.,Lin K, Rath VL, Dai SC, Fletterick RJ, Hwang PK Science. 1996 Sep 13;273(5281):1539-42. PMID:8703213[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
