Required for photoreceptor cell function. The ninaC proteins combines putative serine/threonine-protein kinase and myosin activities (PubMed:2449973). Essential for the expression and stability of the rtp protein in the photoreceptors (PubMed:20107052). The rtp/ninaC complex is required for stability of inad and inac and the normal termination of phototransduction in the retina (PubMed:20739554). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with rtp. Localizes in the cytoplasm or punctate structures within the nuclei in the absence of rtp. Co-localizes with rtp in the rhabdomere membrane. Expressed in the phototransducing compartment of photoreceptor cells, the rhabdomeres (at protein level). In the C-terminal section; belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Myosin family. In the N-terminal section; belongs to the protein kinase superfamily. Ser/Thr protein kinase family.