1jnj
From Proteopedia
NMR solution structure of the human beta2-microglobulin
Structural highlights
DiseaseB2MG_HUMAN Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:241600. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation.[1] Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] FunctionB2MG_HUMAN Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe solution structure of human beta2-microglobulin (beta2-m), the nonpolymorphic component of class I major histocompatibility complex (MHC-I), was determined by (1)H NMR spectroscopy and restrained modeling calculations. Compared to previous structural data obtained from the NMR secondary structure of the isolated protein and the crystal structure of MHC-I, in which the protein is associated to the heavy-chain component, several differences are observed. The most important rearrangements were observed for (1) strands V and VI (loss of the C-terminal and N-terminal end, respectively), (2) interstrand loop V-VI, and (3) strand I, including the N-terminal segment (displacement outward of the molecular core). These modifications can be considered as the prodromes of the amyloid transition. Solvation of the protected regions in MHC-I decreases the tertiary packing by breaking the contiguity of the surface hydrophobic patches at the interface with heavy chain and the nearby region at the surface charge cluster of the C-terminal segment. As a result, the molecule is placed in a state in which even minor charge and solvation changes in response to pH or ionic-strength variations can easily compromise the hydrophobic/hydrophilic balance and trigger the transition into a partially unfolded intermediate that starts with unpairing of strand I and leads to polymerization and precipitation into fibrils or amorphous aggregates. The same mechanism accounts for the partial unfolding and fiber formation subsequent to Cu(2+) binding, which is shown to occur primarily at His 31 and involve partially also His 13, the next available His residue along the partial unfolding pathway. The solution structure of human beta2-microglobulin reveals the prodromes of its amyloid transition.,Verdone G, Corazza A, Viglino P, Pettirossi F, Giorgetti S, Mangione P, Andreola A, Stoppini M, Bellotti V, Esposito G Protein Sci. 2002 Mar;11(3):487-99. PMID:11847272[15] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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Categories: Homo sapiens | Large Structures | Andreola A | Bellotti V | Corazza A | Esposito G | Giorgetti S | Mangione P | Pettirossi F | Stoppini M | Verdone G | Viglino P