Amino terminus

EIectrosta.tlcs. Electrostatic interactions, such as salt bridges, result from the electrostatic attraction that occurs between oppositely charged molecules. These usually involve a single cation, eg, the side chain of Lys or Arg, or the amino terminus, etc, interacting with a single anion, eg, the side chain of Glu or Asp, or the carboxyl terminus, etc. This attractive force is iaversely proportional to the distance between the charges and the dielectric constant of the solvent, as described by Coulomb s law. 

Parvalbumin is a muscle protein with a single polypeptide chain of 109 amino acids. Its function is uncertain, but calcium binding to this protein probably plays a role in muscle relaxation. The helix-loop-helix motif appears three times in this structure, in two of the cases there is a calcium-binding site. Figure 2.13 shows this motif which is called an EF hand because the fifth and sixth helices from the amino terminus in the structure of parvalbumin, which were labeled E and F, are the parts of the structure that were originally used to illustrate calcium binding by this motif. Despite this trivial origin, the name has remained in the literature. 

Figure 6.25 Schematic diagram of the structure of one dimer of phosphofructokinase. Each polypeptide chain is folded Into two domains (blue and red, and green and brown), each of which has an oi/p structure. Helices are labeled A to M and p strands 1 to 11 from the amino terminus of one polypeptide chain, and respectively from A to M and 1 to 11 for the second polypeptide chain. The binding sites of substrate and effector molecules are schematically marked In gray. The effector site of one subunit is linked to the active site of the other subunit of the dimer through the 6-F loop between helix F and strand 6. (Adapted from T. Schlrmer and P.R. Evans, Nature 343 140-145, 1990.)...

Fraser, N. J., Wise, A., Brown, J., McLatchie, L. M., Main, M. J., and Foord, S. M. (1999). The amino terminus of receptor activity modifying proteins is a critical determinant of glycosylation state and ligand binding of calcitonin-like receptor. Mol. Pharmacol. 55 1054-1059. 

Importantly, both incretins when secreted by the intestine are rapidly degraded by the dipeptidyl peptidase IV (DPPFV), which removed the two amino-terminus histidine-alanine residues, thereby, inactivating the incretins. This enzyme is present at the surface of the epithelial intestinal cells and capillaries in the vicinity of the K and L cells secreting GIP and GLP-1, respectively. It is also present in the... 

Parkin is a ubiquitin ligase encoded by a gene affected in autosomal recessive juvenile parkinsonism (AR-JP). This gene is located on chromosome 6 and encodes a protein of 465 amino acid residues with moderate similarity to ubiquitin at the amino terminus and a RING-finger motif at the carboxy terminus. 

In addition to the membrane-inserted core domain of Kv channels, their cytoplasmic domains have important roles for Kv-channel function [5]. Many of these functions are related to subunits assembly, channel trafficking to and from the plasma membrane, and interactions with cytoskeletal components (Fig. la). A tetramerization (T) domain for subunit assembly has been well defined in Shaker-channels, where it is localized in the amino-terminus. Other Kv-channels (e.g., eag, HERG, KvLQTl) may have comparable domains within the cytoplasmic carboxy-terminus. ER retention and retrieval signals have been found... 

Hsp90 is a molecular chaperon required for the refolding of proteins in cells exposed to environmental stress. It contains an ATP-binding pocket in its amino terminus. Several natural products, for example radicicol (230) (Scheme 48), bind to this pocket and inhibit its chaperon function, which is mirrored in enhanced proteosomal degradation of Hsp90 client proteins, so that compounds like 230 are of interest as novel anticancer agents. 

Figure 2. Schematic of HSFl map depicting the DNA binding region at the amino terminus and the regulatory regions for protein-protein interactions in the COOH-ter-...

Asp-A-pro tease The amino terminus sides of aspartic acid and glutamic acid... 

Pepsin The amino terminus sides of phenylalanine, tryptophan and tyramine... 

Like the other paralytic toxins from Conus venom, a-conotoxins are small and very tightly folded, structural features which may be advantageous for rapid paralysis of prey (1). a-Conotoxins are typically 13 to 15 amino acids long with two disulfide bridges (see Table III). In addition to the five a-conotoxins shown, two new a-conotoxins (SIA and SIB) from C. striatus have recently been isolated, sequenced, and chemically synthesized. SIA is very unusual because it is 19 amino acid residues long and it contains 6 cysteine residues, three of which are contiguous near the amino terminus (C. Ramilo et al., unpublished results). 

Stoichactis (Stichodactyla) helianthus. It has recently been shown by CM-cellulose chromatography that heliantholysin consists of four isotoxins having different N-terminal amino acid sequences (Kern and Dunn, in press). Designated I to IV in order of increasing isoelectric pH, toxins I and II had one additional amino acid at the amino terminus than did toxin III. Toxin IV had a seven residue extension at the amino terminus relative to toxin III. Toxin HI and toxin II contributed 83% and 14% of the total hemolytic activity, respectively, and toxins I and FV together about 3%. 

Farzan M, Mirzabekov T, Kolchinsky P, Wyatt R, Cayabyab M, Gerard NP, Gerard C, Sodroski J, Choe H (1999) Tyrosine sulfation of the amino terminus of CCR5 fadlitates HlV-1 entry. Cell 96 667-676... 

Farzan M, Babcock GJ, Vasiheva N, Wright PL, Kipiilov E, Mirzabekov T, Choe H (2002) The role of post-translational modifications of the CXCR4 amino terminus in stromal-derived factor 1 alpha association and HlV-1 entry. J Biol Chem 277 29484—29489... 

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