protein phosphatase 1 regulatory subunit 3B; protein phosphatase 1 regulatory subunit 4; R4; protein phosphatase 1 subunit GL; hepatic glycogen-targeting protein phosphatase 1 regulatory subunit GL (PPP1R3B, PPP1R4)

Function

• acts as a glycogen-targeting subunit for phosphatase PP1
• facilitates interaction of the PP1 with enzymes of glycogen metabolism & regulates its activity
• suppresses the rate at which PP1 dephosphorylates (inactivates) glycogen phosphorylase & enhances the rate at which it activates glycogen synthase & therefore limits glycogen breakdown
• activity is inhibited by PYGL, resulting in inhibition of glycogen synthase & glycogen phosphorylase phosphatase activities of PP1
• dramatically increases basal & insulin-stimulated glycogen synthesis upon overexpression in hepatocytes (putative)
• interacts with glycogen, PPP1CC catalytic subunit of PP1 & PYGL
• associates with glycogen particles
• forms complexes with debranching enzyme, glycogen phosphorylase, glycogen synthase & phosphorylase kinase which is necessary for its regulation of PP1 activity (putative)

Structure

• N-terminal region is required for binding to PP1,
• central region is required for binding to glycogen
• C-terminal region is required for binding to PYGL (putative)
• contains 1 CBM21 domain (carbohydrate binding type-21)

Expression

• moderately-highly expressed in liver
• expressed moderately-predominantly in heart & skeletal muscle & myotubes
• expressed moderately in liver. expressed weakly in placenta, lung & kidney

More general terms

• protein phosphatase-1 regulatory subunit

Component of

• phosphatase-1 (PP1)

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:7966
• UniProt: http://www.uniprot.org/uniprot/Q86XI6.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=79660