Qa-1b

Within molecular and cell biology, Qa-1b is a MHC class I molecule and is the functional homolog of HLA-E in humans. Qa-1b is characterised by its limited polymorphisms and small peptide repertoire. Qa-1b binds to peptides derived from signal peptides of MHC class Ia molecule and interact with the CD94/NKG2 receptors on natural killer cells. The Qa-1b-peptide complex signals natural killer cells not to engage in cell lysis. Despite its homology with HLA-E, it seems that Qa-1b evolved a similar function to HLA-E coincidentally.^{[citation needed]}

v t e Major histocompatibility complex classes
MHC class I	HLA-A HLA-B HLA-C HLA-E HLA-F HLA-G
MHC class II	HLA-DM α β HLA-DO α β HLA-DP α1 β1 HLA-DQ α1 α2 β1 β2 β3 HLA-DR α β1 β3 β4 β5
Other	Human leukocyte antigen Minor histocompatibility antigen Blood transfusion Arrestin Calgranulin Human blood group systems Cell adhesion molecules Cluster of differentiation

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