4po7
Structure of the Sortilin:neurotensin complex at excess neurotensin concentration
Structural highlights
DiseaseSORT_HUMAN Note=A common polymorphism located in a non-coding region between CELSR2 and PSRC1 alters a CEBP transcription factor binding site and is responsible for changes in hepatic expression of SORT1. Altered SORT1 expression in liver affects low density lipoprotein cholesterol levels in plasma and is associated with susceptibility to myocardial infarction. FunctionSORT_HUMAN Functions as a sorting receptor in the Golgi compartment and as a clearance receptor on the cell surface. Required for protein transport from the Golgi apparatus to the lysosomes by a pathway that is independent of the mannose-6-phosphate receptor (M6PR). Also required for protein transport from the Golgi apparatus to the endosomes. Promotes neuronal apoptosis by mediating endocytosis of the proapoptotic precursor forms of BDNF (proBDNF) and NGFB (proNGFB). Also acts as a receptor for neurotensin. May promote mineralization of the extracellular matrix during osteogenic differentiation by scavenging extracellular LPL. Probably required in adipocytes for the formation of specialized storage vesicles containing the glucose transporter SLC2A4/GLUT4 (GLUT4 storage vesicles, or GSVs). These vesicles provide a stable pool of SLC2A4 and confer increased responsiveness to insulin. May also mediate transport from the endoplasmic reticulum to the Golgi.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedSortilin is a multifunctional receptor involved in sorting and apoptosis. We have previously reported a 2.0-A structure of the Vps10 ectodomain in complex with one of its ligands, the tridecapeptide neurotensin. Here we set out to further characterize the structural properties of sortilin and its interaction with neurotensin. To this end, we have determined a new 2.7 A structure using a crystal grown with a 10-fold increased concentration of neurotensin. Here a second peptide fragment was observed within the Vps10 beta-propeller, which may in principle either represent a second molecule of neurotensin or the N-terminal part of the molecule bound at the previously identified binding site. However, in vitro binding experiments strongly favor the latter hypothesis. Neurotensin thus appears to bind with a 1:1 stoichiometry, and whereas the N-terminus does not bind on its own, it enhances the affinity in context of full-length neurotensin. We conclude that the N-terminus of neurotensin probably functions as an affinity enhancer for binding to sortilin by engaging the second binding site. Crystal packing differs partly from the previous structure, which may be due to variations in the degree and pattern of glycosylations. Consequently, a notable hydrophobic loop, not modeled previously, could now be traced. A computational analysis suggests that this and a neighboring loop may insert into the membrane and thus restrain movement of the Vps10 domain. We have, furthermore, mapped all N-linked glycosylations of CHO-expressed human sortilin by mass spectrometry and find that their locations are compatible with membrane insertion of the hydrophobic loops. Revisiting the structure of the Vps10 domain of human sortilin and its interaction with neurotensin.,Quistgaard EM, Groftehauge MK, Madsen P, Pallesen LT, Christensen B, Sorensen ES, Nissen P, Petersen CM, Thirup SS Protein Sci. 2014 Jul 1. doi: 10.1002/pro.2512. PMID:24985322[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||
