Centriole wall protein that localizes to mature centrioles and regulates centriole and cilia biogenesis (PubMed:27246242, PubMed:27588451, PubMed:28242748, PubMed:34259627). Involved in centrosome duplication: required for efficient PLK4 centrosomal localization and PLK4-induced overduplication of centrioles (PubMed:27246242). Involved in cilium biogenesis and controls cilium length (PubMed:27588451). Acts as a regulator of protein stability by preventing ubiquitination of centrosomal proteins, such as CCP110 and tektins (PubMed:28242748, PubMed:34259627). Associates with the EDVP complex, preventing ubiquitination and degradation of CCP110 (PubMed:28242748, PubMed:34259627). Promotes deubiquitination of tektin proteins (TEKT1, TEKT2, TEK3, TEKT4 and TEKT5) via its interaction with USP16 (By similarity). {ECO:0000250|UniProtKB:Q6IRU7, ECO:0000269|PubMed:27246242, ECO:0000269|PubMed:27588451, ECO:0000269|PubMed:28242748, ECO:0000269|PubMed:34259627}. This is the function of Ensembl gene identifier ENSG00000148019 (CEP78, centrosomal protein 78).