Heterodimer with B2M. Expressed in stomach, intestine, uterus, skeletal muscle and heart. In neonatal animals, highly expressed in skin where it localizes to a region of the inner root sheath of hair follicles (at protein level) (PubMed:12370446, PubMed:16920948). Also expressed in thymic medullary epithelial cells (at protein level) (PubMed:12370446, PubMed:16920948). Detected in skeletal muscle, eyes, and submandibular glands (PubMed:12370446). N-glycosylated. Belongs to the MHC class I family. Lacks key residues involved in peptide docking and also does not require TAP (transporter involved in antigen processing) for cell surface expression, suggesting that this is a non-classical MHC class I protein which does not play a role in antigen presentation.