| Structural highlights
Function
CXCL7_HUMAN LA-PF4 stimulates DNA synthesis, mitosis, glycolysis, intracellular cAMP accumulation, prostaglandin E2 secretion, and synthesis of hyaluronic acid and sulfated glycosaminoglycan. It also stimulates the formation and secretion of plasminogen activator by human synovial cells. NAP-2 is a ligand for CXCR1 and CXCR2, and NAP-2, NAP-2(73), NAP-2(74), NAP-2(1-66), and most potent NAP-2(1-63) are chemoattractants and activators for neutrophils. TC-1 and TC-2 are antibacterial proteins, in vitro released from activated platelet alpha-granules. CTAP-III(1-81) is more potent than CTAP-III desensitize chemokine-induced neutrophil activation.[1] [2] [3] [4]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
alpha-Chemokines comprise a family of cytokines that are chemotactic for neutrophils and have a structure similar to platelet factor 4 (PF4), in which the first two cysteine residues are separated by one residue (Cys-X-Cys). The two alpha-chemokines, connective tissue activating peptide-III (CTAP-III) and neutrophil activating peptide-2 (NAP-2), are carboxyl-terminal fragments of platelet basic protein (PBP) that are generated by monocyte-derived proteases. NAP-2 strongly stimulates neutrophils that are present during inflammation whereas its precursors, PBP and CTAP-III, are inactive, although they also possess the highly conserved, amino-terminal sequence, Glu-Leu-Arg (ELR), that is critical for receptor binding. To resolve this conundrum, we have determined the crystal structure of recombinant Asp-CTAP, which has ten fewer amino-terminal residues than CTAP-III but five more than NAP-2. The space group is P2(1)with unit cell dimensions a = 43.8 A, b = 76.8 A, c = 43.8 A, and beta =97.0 degrees, and a tetramer in the asymmetric unit. The molecular replacement method, with the NAP-2 tetramer as a starting model, was used to determine the initial phase information. The final R-factor is 0.196 (Rfree = 0.251) for 2sigma data from 7.0 to 1.75 A resolution. This high-resolution model of Asp-CTAP is the longest defined structure of an alpha-chemokine to date. The electron density map shows an over-all structure for Asp-CTAP that is very similar to that of NAP-2, but with the additional five amino-terminal residues folding back through a type-II turn, thereby stabilizing the oligomeric "inactive" state, and masking the critical ELR receptor binding region that is exposed in the structure of NAP-2.
The amino-terminal residues in the crystal structure of connective tissue activating peptide-III (des10) block the ELR chemotactic sequence.,Malkowski MG, Lazar JB, Johnson PH, Edwards BF J Mol Biol. 1997 Feb 21;266(2):367-80. PMID:9047370[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Krijgsveld J, Zaat SA, Meeldijk J, van Veelen PA, Fang G, Poolman B, Brandt E, Ehlert JE, Kuijpers AJ, Engbers GH, Feijen J, Dankert J. Thrombocidins, microbicidal proteins from human blood platelets, are C-terminal deletion products of CXC chemokines. J Biol Chem. 2000 Jul 7;275(27):20374-81. PMID:10877842
- ↑ Piccardoni P, Evangelista V, Piccoli A, de Gaetano G, Walz A, Cerletti C. Thrombin-activated human platelets release two NAP-2 variants that stimulate polymorphonuclear leukocytes. Thromb Haemost. 1996 Nov;76(5):780-5. PMID:8950790
- ↑ Ehlert JE, Petersen F, Kubbutat MH, Gerdes J, Flad HD, Brandt E. Limited and defined truncation at the C terminus enhances receptor binding and degranulation activity of the neutrophil-activating peptide 2 (NAP-2). Comparison of native and recombinant NAP-2 variants. J Biol Chem. 1995 Mar 17;270(11):6338-44. PMID:7890771
- ↑ Ehlert JE, Gerdes J, Flad HD, Brandt E. Novel C-terminally truncated isoforms of the CXC chemokine beta-thromboglobulin and their impact on neutrophil functions. J Immunol. 1998 Nov 1;161(9):4975-82. PMID:9794434
- ↑ Malkowski MG, Lazar JB, Johnson PH, Edwards BF. The amino-terminal residues in the crystal structure of connective tissue activating peptide-III (des10) block the ELR chemotactic sequence. J Mol Biol. 1997 Feb 21;266(2):367-80. PMID:9047370 doi:10.1006/jmbi.1996.0796
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