Enables cargo receptor activity. Involved in cobalamin metabolic process. Acts upstream of or within regulation of vitamin metabolic process. Located in plasma membrane. Is expressed in several structures, including brain; genitourinary system; heart; immune system; and liver. Used to study methylmalonic acidemia due to transcobalamin receptor defect. Human ortholog(s) of this gene implicated in methylmalonic acidemia due to transcobalamin receptor defect. Orthologous to human CD320 (CD320 molecule). [provided by Alliance of Genome Resources, Apr 2022]