Biomedical subjects

U Kishore

Publications and source records attributed to U Kishore.

23 records · Page 2Linked to original sources

PubMed1997

Clinical relevance of calreticulin in systemic lupus erythematosus.

Calreticulin is an abundant intracellular protein which is proposed to have numerous biological functions. However, there is increasing evidence to suggest that calreticulin plays a multifunctional role as an autoantigen present in patients with systemic lupus erythematosus. In this review we detail some of the recent evidence which indicate that calreticulin may play a supportive role in the formation of the autoantigen complex-Ro/SS-A. In addition, several proposed mechanisms of release and surface expression of calreticulin are described in relation to SLE mediated responses to the autoantigen. In particular, the generation of autoantibodies to specific regions of the protein and the ability of calreticulin to interfere with complement mediated inflammatory processes.

Autoantigens↗

PubMed1996

The alpha-helical neck region of human lung surfactant protein D is essential for the binding of the carbohydrate recognition domains to lipopolysaccharides and phospholipids.

We have expressed the carbohydrate recognition domains (CRDs) of human lung surfactant protein D (SP-D) in Escherichia coli as a trimeric structure held together by the alpha-helical neck region of the molecule. The DNA sequence coding for the neck-region peptide and the CRD of SP-D was subcloned and expressed as a fusion protein containing the E. coli maltose binding protein (MBP). After removal of the MBP, the recombinant structure, containing three CRDs of SP-D, was found to be comparable to native SP-D in terms of carbohydrate binding specificity, the binding to lipopolysaccharides (LPSs) of Gram-negative bacteria, and interaction with phospholipids. The CRD of SP-D, without the neck region peptide, was also expressed and shown to behave as a monomer that showed a very weak affinity for maltose-agarose, LPSs and phospholipids. The alpha-helical neck region on its own showed affinity for phospholipids and thus might contribute to the binding of SP-D to these structures. However, the possibility that hydrophobic patches, which are exposed only in the isolated neck region and not in the intact SP-D, plays a role in neck region-phospholipid interaction, cannot be excluded. The results confirm the importance of the neck region as a trimerizing agent in bringing together three CRDs and suggest that multivalency is important in the strong binding of SP-D to carbohydrate targets.

Binding Sites↗

PubMed1996

Interaction of human lung surfactant proteins A and D with mite (Dermatophagoides pteronyssinus) allergens.

Human lung surfactant proteins A (SP-A) and D (SP-D) are both collagenous C-type lectins which appear to mediate antimicrobial activity by binding to carbohydrates on micro-organisms and to receptors on phagocytic cells. Purified native SP-A and SP-D, isolated from human bronchoalveolar lavage fluid, were found to bind to whole mite extracts (Dermatophagoides pteronyssinus) and the purified allergen Der p I, in a carbohydrate-specific and calcium-dependent manner. Binding was inhibited by ethylenediamine tetra-acetic acid (EDTA) as well as by maltose in the case of SP-D, or mannose in the case of SP-A. A recombinant polypeptide, which trimerized to form the neck region and carbohydrate recognition domains of SP-D, also inhibited the binding of native SP-D to the whole mite extract and Der p I. Both SP-A and SP-D did not bind to deglycosylated whole mite extracts or to recombinant Der p proteins, which lacked carbohydrate residues. These results suggest that the ability of surfactant proteins to bind certain allergens is mediated through their carbohydrate-recognition domains (CRDs) interacting with carbohydrate residues on the allergens. Moreover, SP-A and SP-D were found to inhibit allergen-specific IgE binding to the mite extracts either via steric hindrance or competitive binding. It is therefore possible that SP-A and SP-D may be involved in the modulation of allergen sensitization and/or the development of allergic reactions.

Allergens↗

PubMed1995

A recombinant polypeptide, composed of the alpha-helical neck region and the carbohydrate recognition domain of conglutinin, self-associates to give a functionally intact homotrimer.

A recombinant polypeptide composed of the alpha-helical neck region and carbohydrate recognition domain (CRD) of bovine conglutinin was expressed in Escherichia coli. The recombinant protein formed inclusion bodies but could be solubilised using a denaturation-renaturation cycle based on urea and then purified by affinity chromatography on a TSK-N-acetylglucosamide column. The purified product behaved as a homotrimer in non-dissociating conditions, with three CRDs held together by the alpha-helical neck regions. The trimer, although lacking the N-terminal and collagen regions of the native conglutinin, showed the same binding carbohydrate specificities as the native molecule, for the complement fragment C3b and for lipopolysaccharides derived from Gram-negative bacteria.

Animals↗

PubMed1994

Overexpression of Escherichia coli single stranded DNA binding protein under bacteriophage T 7 promoter.

A recombinant vector for overproduction of the E. coli single stranded DNA binding protein (E. coli SSBP) has been constructed. An E. coli strain carrying this plasmid produces up to 150 mg pure SSBP per litre of bacterial culture in a laboratory shake flask. Electron microscopy of the single stranded DNA complexed with SSBP shows characteristic "beaded string"-like appearance. Strong clustering of protein molecules on ssDNA is indicative of a highly cooperative binding.

Bacteriophage T7↗