6u7m | pdb_00006u7m
Cryo-EM Structure of Helical Lipoprotein Lipase
Structural highlights
Function[LIPL_BOVIN] Key enzyme in triglyceride metabolism. Catalyzes the hydrolysis of triglycerides from circulating chylomicrons and very low density lipoproteins (VLDL), and thereby plays an important role in lipid clearance from the blood stream, lipid utilization and storage. Mediates margination of triglyceride-rich lipoprotein particles in capillaries (By similarity). Recruited to its site of action on the luminal surface of vascular endothelium by binding to GPIHBP1 and cell surface heparan sulfate proteoglycans (PubMed:9188470).[UniProtKB:P06858][1] Publication Abstract from PubMedLipases are enzymes necessary for the proper distribution and utilization of lipids in the human body. Lipoprotein lipase (LPL) is active in capillaries, where it plays a crucial role in preventing dyslipidemia by hydrolyzing triglycerides from packaged lipoproteins. Thirty years ago, the existence of a condensed and inactive LPL oligomer was proposed. Although recent work has shed light on the structure of the LPL monomer, the inactive oligomer remained opaque. Here we present a cryo-EM reconstruction of a helical LPL oligomer at 3.8-A resolution. Helix formation is concentration-dependent, and helices are composed of inactive dihedral LPL dimers. Heparin binding stabilizes LPL helices, and the presence of substrate triggers helix disassembly. Superresolution fluorescent microscopy of endogenous LPL revealed that LPL adopts a filament-like distribution in vesicles. Mutation of one of the helical LPL interaction interfaces causes loss of the filament-like distribution. Taken together, this suggests that LPL is condensed into its inactive helical form for storage in intracellular vesicles. The structure of helical lipoprotein lipase reveals an unexpected twist in lipase storage.,Gunn KH, Roberts BS, Wang F, Strauss JD, Borgnia MJ, Egelman EH, Neher SB Proc Natl Acad Sci U S A. 2020 Apr 24. pii: 1916555117. doi:, 10.1073/pnas.1916555117. PMID:32332168[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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