Required for recruitment of CENPA to centromeres and normal chromosome segregation during mitosis. Homodimer, and heterodimer with OIP5/MIS18B (PubMed:17199038, PubMed:26921242). Identified in a complex containing MIS18A, OIP5/MIS18B, MIS18BP1, RBBP7 and RBBP4 (PubMed:17199038). Associated with centromeres in interphase cells, from late anaphase to the G1 phase. Not detected on centromeres during earlier phases of mitosis. Associated with chromatin. Detected in testis. Belongs to the mis18 family.