Here, we show that MHCⅠA in rhesus macaque can be alternatively spliced, generating a novel MHCⅠA isoform (termed MHCⅠA-sv1) devoid of α3 domain. Despite the absence of β2-microglobulin (β2m), MHCⅠA-sv1 proteins reached the cell surface of K562-transfected cells, as endoglycosidase H-sensitive glycoproteins which could form disulphide-bonded homodimers. Cycloheximide-based protein chase experiments showed that MHCⅠA-sv1 proteins were more stable than full-length MHCⅠA in transiently or stably transfected cell lines. Of particular interest, our studies demonstrated that the MHCⅠA-sv1 could form β2m-free heterodimers with its full-length protein in HEK293-MHCⅠA-sv1/MHCⅠA transfectants. The formation of heterodimer was accompanied by a reduction in full-length MHCⅠA ubiquitination and consequent stabilization of the protein. Taken together, these results demonstrate MHCⅠA-sv1 and MHCⅠA can form a novel heterodimeric complex as a result of the displacement of β2m and also illustrate the relevance of regulated MHCⅠA protein degradation in the β2m-free heterodimerization-dependent control, which may have some implications for the MHCⅠA splice variant in the fine tuning of classical MHCⅠA/TCR and MHCⅠA/KIR interactions.