Molecular adapter which is involved in cilium biogenesis. Part of a functional complex including OFD1 a centriolar protein involved in cilium assembly. Could regulate the cAMP-dependent phosphorylation of OFD1, and its subsequent ubiquitination by PJA2 which ultimately leads to its proteasomal degradation. . This is the function of ENSG00000156787 (TBC1D31, TBC1 domain family member 31).