Non-catalytic component of CHSY1-CHPF2 and CHSY3-CHPF2 chondroitin sulfate synthase complexes. CHPF2 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:12145278, ECO:0000269|PubMed:18316376, ECO:0000269|PubMed:41298522}. This is the function of ENSG00000033100 (CHPF2, chondroitin polymerizing factor 2).