The function of ENSG00000100422 (CERK, ceramide kinase) is as follows. Catalyzes specifically the phosphorylation of ceramide to form ceramide 1-phosphate (PubMed:11956206, PubMed:16269826, PubMed:19168031). Acts efficiently on natural and analog ceramides (C6, C8, C16 ceramides, and C8-dihydroceramide), to a lesser extent on C2- ceramide and C6-dihydroceramide, but not on other lipids, such as various sphingosines (PubMed:11956206, PubMed:16269826, PubMed:17392267, PubMed:19168031). Shows a greater preference for D- erythro isomer of ceramides (PubMed:16269826). Binds phosphoinositides (PubMed:19168031). {ECO:0000269|PubMed:11956206, ECO:0000269|PubMed:16269826, ECO:0000269|PubMed:17392267, ECO:0000269|PubMed:19168031}.