The importance of the left-handed polyproline II (PPII) helical conformation has recently become apparent. This conformation generally is involved in two important functions: protein-protein interactions and structural integrity. PPII helices play vital roles in a variety of processes including signal transduction, transcription, and cell motility. Proline-rich regions of sequence are often ass...

Celiac disease, also known as celiac sprue, is a gluten-induced autoimmune-like disorder of the small intestine, which is strongly associated with HLA-DQ2. The structure of DQ2 complexed with an immunogenic epitope from gluten, QLQPFPQPELPY, has been determined to 2.2-A resolution by x-ray crystallography. The glutamate at P6, which is formed by tissue transglutaminase-catalyzed deamidation, is...

We describe the isolation and characterisation of an insulinotropic peptide from the skin secretions of Agalychnis calcarifer frogs. Peptides in crude secretions obtained by mild electrical stimulation from the dorsal skin surface were purified by reversed-phase HPLC, yielding fractions in two zones with insulin-releasing activity ( p <0.001). The peaks showing greatest in vitro insulin-releasi...

Glucocorticoid-induced leucine zipper (GILZ) is a glucocorticoid responsive protein that links the nuclear factor-kappa B (NFκB) and the glucocorticoid signaling pathways. Functional and binding studies suggest that the proline-rich region at the carboxy terminus of GILZ binds the p65 subunit of NFκB and suppresses the immunoinflammatory response. A widely-used strategy in the discovery of pept...

Intracellular protein interaction domains are essential for eukaryotic signaling. In T cells, the CD2BP2 adaptor binds two membrane-proximal proline-rich motifs in the CD2 cytoplasmic tail via its GYF domain, thereby regulating interleukin-2 production. Here we present the structure of the GYF domain in complex with a CD2 tail peptide. Unlike SH3 domains, which use two surface pockets to accomm...

Regulated interactions between short, unstructured amino acid sequences and modular protein domains are central to cell signaling. Here we use synthetic peptides in "active" (e.g. phosphorylated) and "control" (e.g. non-phosphorylated) forms as baits in affinity pull-down experiments to determine such interactions by quantitative proteomics. Stable isotope labeling by amino acids in cell cultur...

In this work, linear and cyclic disulfide heptapeptides of Longicalycinin A have been successfully synthesized by solid phase methodology with Fmoc /t-Bu and solution phase, respectively. 2-Chlorotrityl chloride resin (2-CTC) was used as a solid support. The synthesized linear disulfide analogue of Longicalycinin A was cleaved from the resin as a protected peptide. The final deprotection was pe...

The pyruvate dehydrogenase (PDH) multienzyme complex of Escherichia coli ( M , 5 x 10') contains multiple copies of three different enzymes which function successively to catalyse the oxidative decarboxylation of pyruvate to acetylCoA (Reed, 1974; Perham, 1983). The structural core of the complex is composed of 24 copies of dihydrolipoamide acetyltransferase (E2p, EC 2.3.1.12) assembled with oc...