Potential regulator of CDK5 activity via its interaction with CDK5R1. Negative regulator of centriole disengagement (licensing) which maintains centriole engagement and cohesion. Involved in regulation of mitotic spindle orientation (By similarity). Plays a role in the spindle checkpoint activation by acting as a transcriptional regulator of both BUBR1 and MAD2 promoter. Required for the recruitment of AKAP9 to centrosomes (By similarity). Plays a role in neurogenesis. Contrary to higher mammalian orthologs, including human, chimpanzee, bovine and dog, does not interact with EB1/MAPRE1, therefore its function in the regulation of microtubule dynamics is unclear (By similarity). Interacts with CDK5R1 (p35 form) (PubMed:10721722). CDK5RAP1, CDK5RAP2 and CDK5RAP3 show competitive binding to CDK5R1. May form a complex with CDK5R1 and CDK5. Interacts (via C-terminus) with PCNT; the interaction is leading to centrosomal localization of CDK5RAP2 and PCNT (By similarity). Interacts with AKAP9; the interaction is leading to Golgi localization of CDK5RAP2 and AKAP9. Interacts with TUBG1; the interaction is leading to the centrosomal localization of CDK5RAP2 and TUBG1. Interacts with TUBGCP3. Interacts with CALM1. Interacts with CDC20. Interacts with CEP68; degradation of CEP68 in early mitosis leads to removal of CDK5RAP2 from the centrosome which promotes centriole disengagement and subsequent centriole separation. Interacts with NCKAP5L. Interacts with LGALS3BP; this interaction may connect the pericentrosomal complex to the gamma-tubulin ring complex (gamma-TuRC) to promote microtubule assembly and acetylation (By similarity). Contrary to human, chimpanzee, bovine and dog orthologous proteins, does not interact with EB1/MAPRE1, possibly due to a divergence at the level of the critical residue 939, which is a proline in MAPRE1-binding orthologs and a leucine in mouse and rat (Probable). Found in the pericentriolar region adhering to the surface of the centrosome and in the region of the centrosomal appendages. Localization to centrosomes versus Golgi apparatus may be cell type-dependent. Due to the probable lack of interaction with EB1/MAPRE1, its localization to microtubule plus ends may not be conserved in rats. Phosphorylated in vitro by CDK5.