1j8e
From Proteopedia
Crystal structure of ligand-binding repeat CR7 from LRP
Structural highlights
Function[LRP1_HUMAN] Endocytic receptor involved in endocytosis and in phagocytosis of apoptotic cells. Required for early embryonic development. Involved in cellular lipid homeostasis. Involved in the plasma clearance of chylomicron remnants and activated LRPAP1 (alpha 2-macroglobulin), as well as the local metabolism of complexes between plasminogen activators and their endogenous inhibitors. May modulate cellular events, such as APP metabolism, kinase-dependent intracellular signaling, neuronal calcium signaling as well as neurotransmission.[1] [2] [3] [4] [5] Functions as a receptor for Pseudomonas aeruginosa exotoxin A.[6] [7] [8] [9] [10] 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 PubMedWe have determined the X-ray crystal structure to 1.8 A resolution of the Ca(2+) complex of complement-like repeat 7 (CR7) from the low-density lipoprotein receptor-related protein (LRP) and characterized its calcium binding properties at pH 7.4 and 5. CR7 occurs in a region of the LRP that binds to the receptor-associated protein, RAP, and other protein ligands in a Ca(2+)-dependent manner. The calcium coordination is identical to that found in LB5 and consists of carboxyls from three conserved aspartates and one conserved glutamate, and the backbone carbonyls of a tryptophan and another aspartate. The overall fold of CR7 is similar to those of CR3 and CR8 from the LRP and LB5 from the LDL receptor, though the low degree of sequence homology of residues not involved in calcium coordination or in disulfide formation results in a distinct pattern of surface residues for each domain, including CR7. The thermodynamic parameters for Ca(2+) binding at both extracellular and endosomal pHs were determined by isothermal titration calorimetry for CR7 and for related complement-like repeats CR3, CR8, and LB5. Although the drop in pH resulted in a reduction in calcium affinity in each case, the changes were very variable in magnitude, being as low as a 2-fold reduction for CR3. This suggests that a pH-dependent change in calcium affinity alone cannot be responsible for the release of bound protein ligands from the LRP at the pH prevailing in the endosome, which in turn requires one or more other pH-dependent effects for regulating protein ligand release. Calcium coordination and pH dependence of the calcium affinity of ligand-binding repeat CR7 from the LRP. Comparison with related domains from the LRP and the LDL receptor.,Simonovic M, Dolmer K, Huang W, Strickland DK, Volz K, Gettins PG Biochemistry. 2001 Dec 18;40(50):15127-34. PMID:11735395[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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