1pfn

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PF4-M2 CHIMERIC MUTANT WITH THE FIRST 10 N-TERMINAL RESIDUES OF R-PF4 REPLACED BY THE N-TERMINAL RESIDUES OF THE IL8 SEQUENCE. MODELS 16-27 OF A 27-MODEL SET.

Overview

Native human platelet factor 4 (PF4) is a homotetrameric protein (70, residues/subunit) known for its anticoagulant heparin binding activity. 2D, 15N--1H HSQC NMR experiments of native PF4 in solution show the presence, of conformational heterogeneity consistent with the formation of, asymmetric homo-tetramers as observed in the X-ray crystal structure of, both human and bovine PF4. A chimeric mutant of PF4 (called PF4-M2) which, substitutes the first 11 N-terminal residues for the first eight residues, from homologous interleukin-8 forms symmetric homo-tetramers with, essentially the same heparin binding activity as native PF4. The solution, structure of PF4-M2 has been investigated by using two- and, three-dimensional 1H- and 15N-NMR spectroscopy and NOE-restrained, simulated annealing molecular dynamics. As with other members of the CXC, chemokine family whose structures are known, the PF4-M2 subunit monomer, consists of a mostly hydrophobic, triple-stranded antiparallel beta-sheet, onto which is folded an amphipathic C-terminal helix and a less periodic, N-terminal domain. Although N-terminal substitution with the less acidic, interleukin-8 sequence most affects the quarternary structure relative to, native PF4 at the AC and AD dimer interfaces, AB dimer stability is, weakened as reflected in reduced equilibrium association binding, constants.

About this Structure

1PFN is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

NMR solution structure of the 32-kDa platelet factor 4 ELR-motif N-terminal chimera: a symmetric tetramer., Mayo KH, Roongta V, Ilyina E, Milius R, Barker S, Quinlan C, La Rosa G, Daly TJ, Biochemistry. 1995 Sep 12;34(36):11399-409. PMID:7547867

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