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STRUCTURE OF THE MHC CLASS I HOMOLOG MIC-A, A GAMMADELTA T CELL LIGAND
Structural highlights
DiseaseMICA_HUMAN Note=Anti-MICA antibodies and ligand shedding are involved in the progression of monoclonal gammopathy of undetermined significance (MGUS)to multiple myeloma. Genetic variations in MICA may be a cause of susceptibility to psoriasis type 1 (PSORS1) [MIM:177900. Psoriasis is a common, chronic inflammatory disease of the skin with multifactorial etiology. It is characterized by red, scaly plaques usually found on the scalp, elbows and knees. These lesions are caused by abnormal keratinocyte proliferation and infiltration of inflammatory cells into the dermis and epidermis. Genetic variation in MICA is a cause of susceptibility to psoriatic arthritis (PSORAS) [MIM:607507. PSORAS is an inflammatory, seronegative arthritis associated with psoriasis. It is a heterogeneous disorder ranging from a mild, non-destructive disease to a severe, progressive, erosive arthropathy. Five types of psoriatic arthritis have been defined: asymmetrical oligoarthritis characterized by primary involvement of the small joints of the fingers or toes; asymmetrical arthritis which involves the joints of the extremities; symmetrical polyarthritis characterized by a rheumatoidlike pattern that can involve hands, wrists, ankles, and feet; arthritis mutilans, which is a rare but deforming and destructive condition; arthritis of the sacroiliac joints and spine (psoriatic spondylitis). FunctionMICA_HUMAN Seems to have no role in antigen presentation. Acts as a stress-induced self-antigen that is recognized by gamma delta T-cells. Ligand for the KLRK1/NKG2D receptor. Binding to KLRK1 leads to cell lysis.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe major histocompatibility complex (MHC) class I homolog MIC-A functions as a stress-inducible antigen that is recognized by a subset of gammadelta T cells independent of beta2-microglobulin and bound peptides. Its crystal structure reveals a dramatically altered MHC class I fold, both in detail and overall domain organization. The only remnant of a peptide-binding groove is a small cavity formed as the result of disordering a large section of one of the groove-defining helices. Loss of beta2-microglobulin binding is due to a restructuring of the interaction interfaces. Structural mapping of sequence variation suggests potential receptor binding sites on the underside of the platform on the side opposite of the surface recognized by alphabeta T cell receptors on MHC class I-peptide complexes. Crystal structure of the MHC class I homolog MIC-A, a gammadelta T cell ligand.,Li P, Willie ST, Bauer S, Morris DL, Spies T, Strong RK Immunity. 1999 May;10(5):577-84. PMID:10367903[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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