8vvm
Structure of FabS1CE1-EPR1-1 in complex with the erythropoietin receptor
Structural highlights
DiseaseEPOR_HUMAN Defects in EPOR are the cause of familial erythrocytosis type 1 (ECYT1) [MIM:133100. ECYT1 is an autosomal dominant disorder characterized by increased serum red blood cell mass, elevated hemoglobin and hematocrit, hypersensitivity of erythroid progenitors to erythropoietin, erythropoietin low serum levels, and no increase in platelets nor leukocytes. It has a relatively benign course and does not progress to leukemia.[1] [2] [3] FunctionEPOR_HUMAN Receptor for erythropoietin. Mediates erythropoietin-induced erythroblast proliferation and differentiation. Upon EPO stimulation, EPOR dimerizes triggering the JAK2/STAT5 signaling cascade. In some cell types, can also activate STAT1 and STAT3. May also activate the LYN tyrosine kinase. Isoform EPOR-T acts as a dominant-negative receptor of EPOR-mediated signaling. Publication Abstract from PubMedIt has been shown previously that a set of three modifications-termed S1, Crystal Kappa, and elbow-act synergistically to improve the crystallizability of an antigen-binding fragment (Fab) framework. Here, we prepared a phage-displayed library and performed crystallization screenings to identify additional substitutions-located near the heavy-chain elbow region-which cooperate with the S1, Crystal Kappa, and elbow modifications to increase expression and improve crystallizability of the Fab framework even further. One substitution (K141Q) supports the signature Crystal Kappa-mediated Fab:Fab crystal lattice packing interaction. Another substitution (E172G) improves the compatibility of the elbow modification with the Fab framework by alleviating some of the strain incurred by the shortened and bulkier elbow linker region. A third substitution (F170W) generates a split-Fab conformation, resulting in a powerful crystal lattice packing interaction comprising the biological interaction interface between the variable heavy and light chain domains. In sum, we have used K141Q, E172G, and F170W substitutions-which complement the S1, Crystal Kappa, and elbow modifications-to generate a set of highly crystallizable Fab frameworks that can be used as chaperones to enable facile elucidation of Fab:antigen complex structures by x-ray crystallography. Antigen-binding fragments with improved crystal lattice packing and enhanced conformational flexibility at the elbow region as crystallization chaperones.,Bruce HA, Singer AU, Blazer LL, Luu K, Ploder L, Pavlenco A, Kurinov I, Adams JJ, Sidhu SS Protein Sci. 2024 Jul;33(7):e5081. doi: 10.1002/pro.5081. PMID:38924648[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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