1IOJ

HUMAN APOLIPOPROTEIN C-I, NMR, 18 STRUCTURES

Summary for 1IOJ

• Entry DOI: 10.2210/pdb1ioj/pdb
• Descriptor: APOC-I (1 entity in total)
• Functional Keywords: apolipoprotein, amphipathic helix, lipid association, lcat activation
• Biological source: Homo sapiens (human)
• Cellular location: Secreted : P02654
• Total number of polymer chains: 1
• Total formula weight: 6642.59

Authors

Rozek, A.,Sparrow, J.T.,Weisgraber, K.H.,Cushley, R.J. (deposition date: 1998-05-12, release date: 1998-08-12, Last modification date: 2024-05-01)

Primary citation

Rozek, A.,Sparrow, J.T.,Weisgraber, K.H.,Cushley, R.J.
Conformation of human apolipoprotein C-I in a lipid-mimetic environment determined by CD and NMR spectroscopy.
Biochemistry, 38:14475-14484, 1999

PubMed Abstract: The high-resolution conformation of human apoC-I in complexes with sodium dodecyl sulfate (SDS) is presented. As estimated from CD data, apoC-I adopts 54% helical secondary structure when bound to SDS, which is similar to the helical content previously found with phospholipids. The NMR-derived conformation of apoC-I is composed of two amphipathic helices, residues 7-29 and 38-52, separated by a flexible linker. The N-terminal helix contains a mobile hinge involving residues 12-15. The hydrophobic side chains cluster on the nonpolar face of both helices, thus forming two discrete lipid-binding sites in the N-terminal helix and one in the C-terminal helix. As suggested by amide proton resonance line widths and deuterium exchange rates, the N-terminal helix is more flexible and may bind less tightly to the detergent than the C-terminal helix. The different mobility of both helices appears to be related to side-chain composition, rather than length of the amphipathic helix, and may play a role in the function of apoC-I as an activator of lecithin:cholesterol acyltransferase (LCAT). A model is suggested in which the C-terminal helix serves as a lipid anchor while the N-terminal helix may hinge off the lipid surface to make specific contacts with LCAT.

PubMed: 10545169
DOI: 10.1021/bi982966h

Experimental method

SOLUTION NMR