Showing papers on "Protein–protein interaction published in 1989"

Oligosaccharide–Protein Interactions: A Three-Dimensional View

Abstract: For carbohydrates to serve as recognition elements in cellular function, there must be 'receptors' which are capable of distinguishing between the multitude of oligosaccharide structures generated by a cell Generally these receptors are assumed to be proteins, and the plant lectins have been used as model systems to examine the molecular basis for specificity in such interactions Three aspects of the specificity of oligosaccharide-protein interactions will be discussed: (1) the conformational flexibility of oligosaccharides will be demonstrated through a quantitative analysis of nuclear magnetic resonance measurements; (2) a comparison of the measured and calculated values for the entropy barrier to oligosaccharide binding will be used to argue that the barrier arises from a loss of this conformational flexibility upon binding to the lectin (this conclusion is also supported by X-ray crystallographic studies); and (3) the thermodynamic model can be extended to the binding of glycoproteins to receptors and the high affinity of these interactions explained by either multivalency or fixation of the oligosaccharide in the 'correct' three-dimensional structure through interaction with the protein moiety

Host proteins that bind to or mimic SV40 large T antigen: using antibodies to look at protein interactions and their significance.

Abstract: To study cellular proteins which interact with T we chose to use an immunochemical approach which initially involved the raising and mapping of monoclonal antibodies which bind to T We have successfully exploited some of the properties of these antibodies to map functional domains of T The aim of this study was to define the interactions of two particular host proteins, p53 and DNA polymerase α, with large T and to explore the existence of cellular homologues of large T

Strategies in Regulation of Protein Associations of the Spectrin-Based Membrane Skeleton

Abstract: The spectrin-based membrane skeleton of nonerythroid cells exhibits an unsuspected variety in protein interactions and regulatory mechanisms. Spectrin has at least two options in linkage to the membrane: ankyrin-mediated interaction with integral membrane proteins and direct linkages with ankyrin-independent sites. Ankyrin includes at least two families of functionally distinct isoforms, a general isoform expressed in many cells and a specialized isoform expressed in a limited number of cells and localized in a highly polarized distribution in these cells. Proteins likely to associate with the specialized isoforms of ankyrin based on association in vitro assays and co-localization in cells include the anion exchanger of erythrocytes and collecting ducts of kidney, the Na/K ATPase in distal tubule cells of kidney, and the voltage-dependent sodium channel in neuron. An additional mechanism for ankyrin diversity is processed variants of ankyrin with deleted regulatory domains that express binding sites unavailable to unprocessed ankyrinc Spectrin also can interact with high affinity with protein sites in synaptosomes and other membranes that are independent of ankyrin. Calmodulin in the presence of submicromolar concentrations of calcium is a competitive inhibitor of direct binding of spectrin to synaptosomal membranes but does not affect spectrin-ankyrin interactions. Thus the potential exists for differential regulation of spectrin-membrane interactions. The assembly state of the spectrin-actin lattice may also vary in certain cells. Adducin, a protein that promotes spectrin-actin interactions, is concentrated at sites of cell-cell contact in certain epithelial cells. These studies provide a low-resolution view of the spectrin skeleton and emphasize the possibilities for participation of this structure in a variety of functions including maintenance of specialized cell domains and participation in dynamic calcium-regulated processes.

Protein-Protein Interactions and Immune Recognition

Abstract: Specific interactions between proteins are fundamental to many biological phenomena. It is widely held that selection for a particular function has shaped the interacting molecules to provide the appropriate degree of specificity. Furthermore, in most cases there is a sense of ‘uniqueness’ about a particular interaction in which one structure is associated with only one function.