Catalyzes specifically the phosphorylation of ceramide to form ceramide 1-phosphate. Possesses activity on ceramide analog (C6 synthetic ceramide) in vitro. Ceramide is a critical sphingolipid metabolite that induces programmed cell death (PCD) in plants and ceramide-1-phosphate has a PCD suppressive effect. Thus, ceramide phosphorylation plays a role in the modulation of PCD and CERK activity is crucial for the maintenance of cell viability. an N-acylsphing-4-enine + ATP = ADP + an N-acylsphing-4-enine 1-phosphate + H(+) Optimum pH is 7.0 (at 40 degrees Celsius). Optimum temperature is 40 degrees Celsius. Highly expressed in leaves and at lower levels in stems. Overexpression of CERK in the Arabidopsis mutant acd5 restores wild-type phenotype.