Centromeric protein that plays a central role in the incorporation and maintenance of histone H3-like variant CENPA at centromeres. Acts as a specific chaperone for CENPA and is required for the incorporation of newly synthesized CENPA molecules into nucleosomes at replicated centromeres. Prevents CENPA-H4 tetramerization and prevents premature DNA binding by the CENPA-H4 tetramer. Directly binds Holliday junctions. Interacts with CENPA (via CATD domain); the interaction is direct and specific for CENPA since it does not interact with H3.1- or H3.3-containing nucleosomes (PubMed:16622419, PubMed:19410544, PubMed:19410545). Heterotrimer composed of HJURP, CENPA and histone H4, where HJURP interacts with the dimer formed by CENPA and histone H4 and prevents tetramerization of CENPA and H4 (PubMed:21478274). Identified in a centromere complex containing histones H2A, H2B and H4, and at least CENPA, CENPB, CENPC, CENPT, CENPN, HJURP, SUPT16H, SSRP1 and RSF1 (PubMed:27499292). Interacts with 14-3-3 family members in a phosphorylation-dependent manner (PubMed:17256767). Interacts with MSH5 and NBN (PubMed:17823411). Localizes in centromeres during late telophase and early G1, when CENPA nucleosomes are assembled. Localizes to nucleolus during S phase, nucleolus site being often related to storage. According to PubMed:17256767, highly expressed in the thymus with lower levels in the placenta, small intestine, liver, skeletal muscle, and colon. According to PubMed:17823411, highly expressed in testis, and at a relatively lower level in thymus and bone marrow. Significantly overexpressed in many lung cancer samples, compared with normal lung. Truncated C-terminus.