Acyl carrier protein

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Streptomyces coelicolor actinorhodin polyketide synthase acyl carrier protein - PDB 2AF8

The acyl carrier protein (ACP) is an important component in both fatty acid and polyketide biosynthesis with the growing chain bound during synthesis as a thiol ester at the distal thiol of a 4'-phophopantethiene moiety. The protein is expressed in the inactive apo form and the 4'-phosphopantetheine moiety must be post-translationally attached to a conserved serine residue on the ACP by the action of holo-acyl carrier protein synthase (ACPS) a phosphopantetheinyl transferase.

4'-Phosphopantetheine is an essential prosthetic group of several acyl carrier proteins involved in pathways of primary and secondary metabolism including the acyl carrier proteins (ACP) of fatty acid synthases, ACP of polyketide synthases, and peptidyl carrier proteins (PCP) and aryl carrier proteins (ArCP) of nonribosomal peptide synthetases (NRPS). Phosphopantetheine fulfils two demands in these biosynthetic pathways. First, the intermediates remain covalently linked to the synthases (or synthetases) in an energy-rich linkage. Second, the flexibility and length of phosphopantetheine chain (approximately 2 nm) allows the covalently-tethered intermediates to have access to spatially-distinct enzyme-active sites. This increases the effective molarity of the intermediate and allows an assemblyline-like process.

The ACPs are small negatively-charged α-helical bundle proteins with a high degree of structural and amino acid similarity. The structures of a number of acyl carrier proteins have been solved using various NMR and crystallography techniques.

The ACPs are related in structure and mechanism to the peptidyl carrier proteins (PCP) from nonribosomal peptide synthases.

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MeSH Acyl+Carrier+Protein

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v • d • e Proteins: carrier proteins

Hormone	Follistatin - Growth hormone binding protein - Insulin-like growth factor binding protein - Neurophysins (Neurophysin I, II) Sex hormone binding globulin/Androgen binding protein - Transcortin - Thyroxine-binding globulin - Transthyretin

Metal/element	calcium (Calcium-binding protein, Calmodulin-binding proteins) - copper (Ceruloplasmin) - iron (Iron-binding proteins, Transferrin receptor)

Vitamin	Retinol binding protein (4) - Transcobalamin

Other	Acyl carrier protein - Adaptor protein - Cholesterylester transfer protein - F-box protein - GTP-binding protein - Latent TGF-beta binding protein - Light-harvesting complex - Membrane transport protein