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. Together with EB1/MAPRE1, may promote microtubule polymerization, bundle formation, growth and dynamics at the plus ends. Regulates centrosomal maturation by recruitment of the gamma-tubulin ring complex (gamma-TuRC) onto centrosomes (By similarity). In complex with PDE4DIP, MAPRE1 and AKAP9, contributes to microtubules nucleation and extension from the centrosome to the cell periphery. Required for the recruitment of AKAP9 to centrosomes (By similarity). Plays a role in neurogenesis (By similarity). Interacts with CDK5R1 (p35 form). CDK5RAP1, CDK5RAP2 and CDK5RAP3 show competitive binding to CDK5R1. May form a complex with CDK5R1 and CDK5 (By similarity). Interacts with pericentrin/PCNT; the interaction is leading to centrosomal and Golgi localization of CDK5RAP2 and PCNT. Interacts with AKAP9; the interaction targets CDK5RAP2 and AKAP9 to Golgi apparatus. Interacts with MAPRE1; the interaction is direct and targets CDK5RAP2 and EB1/MAPRE1 to microtubule plus ends. 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. Forms a pericentrosomal complex with AKAP9, MAPRE1 and PDE4DIP; within this complex, MAPRE1 binding to CDK5RAP2 may be mediated by PDE4DIP. Interaction with PDE4DIP is PDE4DIP isoform-specific. 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). Found in the pericentriolar region adhering to the surface of the centrosome and in the region of the centrosomal appendages. Localizes to microtubule plus ends in the presence of EB1/MAPRE1. Localization to centrosomes versus Golgi apparatus may be cell type-dependent. Phosphorylated in vitro by CDK5.