Protein phosphatase 1 regulatory subunit 3C (PPP1R3C, PTG) binds to glycogen particles containing GYG2 (glycogenin 2) and GYS2 (glycogen synthase 2). PPP1R3C appears to function as a scaffolding protein to mediate association of other proteins with glycogen granules and to promote the synthesis of glycogen (Worby et al. 2008). This reaction, involving GYG and GYS isoforms largely expressed in the liver has not been studied in detail but is inferred from the better-characterized one involving GYG1- and GYS1-containing glycogen particles ("muscle" isoforms, widely expressed in the body outside the liver).