Forms a homodimer or heterodimer with other members of the family. Isoform 2 is expressed at higher levels in kidney and brain than in liver, lung, testis and heart. Within the brain, isoform 2 is highly expressed in the granular layer of the cerebellum, the cortex and the hippocampus. In embryos, isoform 2 is expressed in the epithelium of the developing intestine, stomach, olfactory epithelium, neuronal layers of the retina, salivary gland, kidney and dorsal root ganglion. Belongs to the TPD52 family.