Predicted to enable transmembrane signaling receptor activity. Acts upstream of or within inhibition of cysteine-type endopeptidase activity involved in apoptotic process; negative regulation of extrinsic apoptotic signaling pathway; and negative regulation of lymphocyte apoptotic process. Located in external side of plasma membrane. Orthologous to human FCMR (Fc fragment of IgM receptor). [provided by Alliance of Genome Resources, Apr 2022]