Probable interaction between S100A7 and E-FABP in the cytosol of human keratinocytes from psoriatic scales

The overexpression of E-FABP and S100A7 in lesional psoriatic skin suggests a possible link with this hyperproliferative skin disease. In order to investigate a role for the proteins in this disease, the purifications for both proteins were re-analyzed. Moreover, a specific antiserum directed against purified human S100A7 was generated. By SDS-PAGE immunoblotting we show that E-FABP and S100A7 are expressed in cultured human differentiating keratinocytes and confirm their overexpression in psoriatic scales. Gel filtration and non-denaturing PAGE revealed that S100A7 co-purified with E-FABP, indicating an association between the two proteins. Ion-exchange chromatography resulted in the dissociation of the complex. Finally, immunoprecipitations using antiserum against E-FABP revealed that S100A7 co-immunoprecipitated with E-FABP from protein extracts of psoriatic scales. These data indicate that E-FABP and S100A7 might form a complex in the cytosol of human keratinocytes.     

Refined mapping of the gene for thiamine-responsive megaloblastic anemia syndrome and evidence for genetic homogeneity

Thiamine-responsive megaloblastic anemia (TRMA, also known as Rogers syndrome, OMIM 249270) is a rare autosomal recessive disorder characterized by a triad of megaloblastic anemia, diabetes mellitus, and sensorineural deafness. Patients respond, to varying degrees, to treatment with megadoses of thiamine. We have recently shown genetic linkage of the TRMA gene to a 16-centimorgan (cM) region on 1q23.2–1q23.3 based on the analysis of four large, inbred families of Alaskan, Italian, and Israeli-Arab origin. Here we narrow the TRMA interval down to 4 cM based on genetic recombination, homozygosity mapping, and linkage disequilibrium (highest LOD score of 12.5 at D1S2799, at a recombination fraction of 0). We provide further evidence that the TRMA gene is located in this region and confirm the homogeneity of the disease. In this analysis, we genotyped seven additional families of diverse ethnic origin (Pakistani, Indian, Italian, Brazilian, and Japanese), and analyzed additional markers in two previously reported families showing evidence of linkage disequilibrium in a large area of their haplotypes. The multi-system manifestations of TRMA suggest that thiamine has a pivotal role in a multiplicity of physiological processes. Mapping the TRMA gene and understanding the molecular basis of the disease might, thus, shed light on the role of thiamine in common disorders such as deafness, anemia, and diabetes. Received: 16 April 1998 / Accepted: 6 July 1998     

Purification and Characterization of a Human Brain Galectin-1 Ligand

Abstract: Our previous studies have characterized an endogenous lectin from human brain identified as galectin-1. A soluble ligand of galectin-1 was purified from human brain by affinity chromatography and preparative electrophoresis. The purified ligand (termed HBGp82, for human brain galectin-1-binding polypeptide of 82,000 daltons) has an apparent molecular mass of 82 kDa and is glycosylated by N -linked biantennary complex structures. HBGp82 was partially characterized by microsequencing of peptide fragments. Similar peptides were found in a heat shock of protein of 90,000 daltons, hsp90. However, comparison of apparent molecular weights and matrix-assisted laser desorption mass spectrometry clearly showed that HBGp82 differs to some degree from hsp90.     

Study of amide-proton exchange of Escherichia coli melibiose permease by attenuated total reflection-Fourier transform infrared spectroscopy: evidence of structure modulation by substrate binding.

The accessibility of Escherichia coli melibiose permease to aqueous solvent was studied following hydrogen-deuterium exchange kinetics monitored by attenuated total reflection-Fourier transform infrared spectroscopy under four distinct conditions where MelB forms different complexes with its substrates (H(+), Na(+), melibiose). Analysis of the amide II band upon (2)H(2)O exposure discloses a significant sugar protection of the protein against aqueous solvent, resulting in an 8% less exchange of the corresponding H(+)*melibiose*MelB complex compared with the protein in the absence of sugar. Investigation of the amide I exchange reveals clear substrate effects on beta-sheet accessibility, with the complex H(+)*melibiose*MelB being the most protected state against exchange, followed by Na(+)*melibiose*MelB. Although of smaller magnitude, similar changes in alpha-helices plus non-ordered structures are detected. Finally, no differences are observed when analyzing reverse turn structures. The results suggest that sugar binding induces a remarkable compactness of the carrier's structure, affecting mainly beta-sheet domains of the transporter, which, according to secondary structure predictions, may include cytoplasmic loops 4-5 and 10-11. A possible catalytic role of these two loops in the functioning of MelB is hypothesized.