Non-catalytic component of CHSY1-CHPF2 and CHSY3-CHPF2 chondroitin sulfate synthase complexes. CHPF associates with catalytically active chondroitin synthases (CHSY1/3) within heterodimeric complexes. Plays an essential role for the formation of a stable and functional chondroitin sulfate polymerase complexes. {ECO:0000269|PubMed:12716890, ECO:0000269|PubMed:12761225, ECO:0000269|PubMed:41298522}. [Isoform 2]: May facilitate PRKN transport into the mitochondria. In collaboration with PRKN, may enhance cell viability and protect cells from oxidative stress. . This is the function of Ensembl gene identifier ENSG00000123989 (CHPF, chondroitin polymerizing factor).