Complex formation of cytochrome C with a calixarene carboxylic acid derivative: a novel solubilization method for biomolecules in organic media

A calixarene carboxylic acid derivative has been found to form a complex with the cationic protein cytochrome c. The solubilized cytochrome c was stable and showed peroxidase activity in chloroform. The calix[6]arene and the calix[8]arene achieved quantitative extraction of the protein. The calix[6]arene, whose cavity is well-fitted to a protonated amino group, exhibited a selectivity to lysine-rich proteins due to the recognition of the epsilon-amino groups in lysine residues on the surface of the protein. This is the first report showing protein extraction by calixarenes. The solubilized cytochrome c could catalyze an oxidative reaction in organic solvents. This host compound functions as a novel solubilization tool for biomolecules and a separation tool for lysine-rich proteins.     

Studies of cargo delivery to the vacuole mediated by autophagosomes in Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, aminopeptidase I (API), a vacuolar hydrolase, is selectively transported to the vacuole via the autophagosome. API forms a cytosol to vacuole targeting (Cvt) complex in the cytoplasm. The complex is engulfed by the autophagosome under starvation conditions. In this study, the Cvt complex is visualized as a dot in the cytoplasm by fluorescence microscopy with API-GFP. The Cvt complex associates with the preautophagosomal structure (PAS), which plays a central role in autophagosome formation. In a Deltacvt19 mutant, which is specifically defective in API transport, but not in autophagy, the Cvt complex forms normally but never associates with the PAS. This indicates that Cvt19p mediates association between the Cvt complex and the PAS.     

Sequential activation of Notch family receptors during mouse spermatogenesis

The expression pattern of Notch family receptors during mouse spermatogenesis was examined by immunohistochemistry. The entire cytoplasm of spermatogonia, spermatocytes and spermatids showed staining with antibodies against extracellular domains of Notch1, 2 and 4. In contrast, the nuclei of spermatogonia showed staining with an antibody against the intracellular domain of Notch3, and the nuclei of spermatocytes and spermatids showed staining with antibodies against the intracellular domains of Notch1 and 4. During regeneration of spermatogonia in busulfan-treated mice, the nuclei of all proliferating cells showed staining for the intracellular domain of Notch3. Western blot analysis showed that the molecular weights of the intracellular domains of Notch1 and 3 localizing in the nuclear fraction were smaller than those in the cytoplasmic fraction. This was consistent with the theory that the intracellular domain of Notch was cleaved in the cytoplasm and translocated to the nucleus. These results suggest that different Notch signals are sequentially activated during mouse spermatogenesis and control the proliferation and differentiation of spermatogenic stem cells.     

An A/G polymorphism of core 2 branching enzyme gene is associated with prostate cancer

The expression of core 2 beta1,6-N-acetylglucosaminyltransferase-1 (C2GnT) is associated with development and progression of malignancy. Sequence analysis showed that the codon 152 of C2GnT has a polymorphism having GTT encoding valine or ATT encoding isoleucine. By examining the polymorphism in prostate cancer and benign prostatic hyperplasia patients, we found that the C2GnT G allele was more frequently observed in the prostate cancer group (p=0.015) than the control group. Men with the GG genotype had a 3.60-fold increased risk of prostate cancer, and men with the AG genotype had a 1.58-fold increased risk of prostate cancer compared with those with the AA genotype. The G allele was found to have a gene dosage effect for prostate cancer risk. No such risk was associated for benign prostatic hyperplasia. These results demonstrate that C2GnT A/G polymorphism is associated with the susceptibility to prostate cancer in a Japanese population.     

A novel Giraffidae-specific interspersed repeat with a microsatellite, originally found in an intron of a ruminant paralogous p97bcnt gene

The ruminant-specific p97bcnt gene (bcnt^p97) is a paralogous gene that includes a region derived from a retrotransposable element 1 (RTE-1). The region comprises an exon (RTE-1 exon) encoding 325 amino acids in the middle of the p97bcnt protein. To understand how the bcnt^p97 paralog evolved, we examined its organization in several ruminants. We found a 700-base pair (bp) insert in the 5′ intron of the RTE-1 exon in giraffe bcnt^p97. This insert is missing in the corresponding regions of bovine and sika deer. Furthermore, the sequence of the insert is interspersed in the genome of giraffe but not bovine and also contains a (GA)n microsatellite. A highly homologous insert harboring significantly different (GA)n microsatellite was detected in the corresponding region of okapi bcnt^p97. Therefore, the interspersed fragments with (GA)n microsatellite might serve as a marker for tracking how duplicated genes evolve in a family-specific manner.