CRYSTAL STRUCTURE OF RECOMBINANT HUMAN PLATELET FACTOR 4
[PLF4_HUMAN] Released during platelet aggregation. Neutralizes the anticoagulant effect of heparin because it binds more strongly to heparin than to the chondroitin-4-sulfate chains of the carrier molecule. Chemotactic for neutrophils and monocytes. Inhibits endothelial cell proliferation, the short form is a more potent inhibitor than the longer form.
Publication Abstract from PubMed
The crystal structure of human platelet factor 4 (PF4) has been solved to a resolution of 2.4 A by molecular replacement and refined to an R-factor of 24.1%. The structure consists of four polypeptide chains which form a tetrameric unit. N-terminal residues, previously defined as a random coil or extended loop region, form antiparallel beta-sheet-like structures that form noncovalent associations between dimers. These antiparallel beta-sheet-like structures are positioned lateral to the beta-bilayer motif and stabilize the tetrameric unit. A positively charged ring of lysine and arginine side chains encircles the PF4 tetramer sphere, presenting multiple potential sites and orientations for heparin binding. The electrostatic interactions of multiply charged amino acid side chains and hydrogen bonding interactions at the AB/CD dimer interface serve to stabilize the tetrameric structure further.
Crystal structure of recombinant human platelet factor 4.,Zhang X, Chen L, Bancroft DP, Lai CK, Maione TE Biochemistry. 1994 Jul 12;33(27):8361-6. PMID:8031770
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.