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PubMed1993

The HOX complex neighbored by the EVX gene, as well as two other homeobox-containing genes, the GBX-class and the EN-class, are located on the same chromosomes 2 and 7 in humans.

Two newly identified human homeobox-containing genes, GBX1 and GBX2, are closely related genes, as are members of the other homeobox genes, EN-1 and EN-2. GBX1 and EN-2 have been mapped to chromosome 7q36. The present study shows that GBX2 was mapped to chromosome 2q37. EN-1 was mapped to chromosome 2q14. Moreover, two HOX complexes neighbored by the EVX gene, HOXA and HOXD, are located at chromosome 7p15-p14 and 2q31-q37, respectively. Thus, it is possible that these homeobox genes were linked to each other on an ancestral genome and that the ancestral chromosome segment was duplicated during evolution.

Amino Acid Sequence↗
PubMed1988

Expression of MHC class I and class I-like gene products on the cell membrane of mature and immature T cells.

Beta 2-microglobulin (beta 2m) constitutes the 12 kD light chain of the MHC-encoded 43-kD glycoprotein HLA-ABC molecules, which are expressed on most nucleated cells. The T6 (CD1a) antigen is expressed on thymocytes in reciprocal manner to HLA-ABC, having a similar structure to the HLA-ABC molecule. We have determined the expression of beta 2m, HLA-ABC and the T6 antigen on the cell-surface of CD1a+ and CD1a- thymocytes (defined by NA1/34 expression), and have shown that despite immunophenotypic differences between these two stages of thymic maturation, the quantity of beta 2m-associated molecules expressed was not significantly different. The nature of the heavy (alpha) chain associated with beta 2m, however, differed since HLA-ABC had largely replaced T6 on the surface of CD1a- thymocytes. We also determined the expression of beta 2m and HLA-ABC on the surface of peripheral blood CD4+ and CD8+ T-cells, and showed that the CD8+ population expressed higher levels of these antigens than CD4+ T-cells, with no detectable excess beta 2m over HLA-ABC for either subpopulation. In addition, thymocytes expressed fewer beta 2m-associated determinants than peripheral blood T-cells. These results indicate an increase in the expression of beta 2m-associated molecules with differentiation from thymic to peripheral T-cell, with a further increase in such molecules expressed on the CD8+ compared to the CD4+ peripheral T-cell subpopulation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2006

Class-1 release factor eRF1 promotes GTP binding by class-2 release factor eRF3.

In eukaryotes, termination of mRNA translation is triggered by the essential polypeptide chain release factors eRF1, recognizing all three stop codons, and eRF3, a member of the GTPase superfamily with a role that has remained opaque. We have studied the kinetic and thermodynamic parameters of the interactions between eRF3 and GTP, GDP and the non-hydrolysable GTP analogue GDPNP in the presence (K(D)(GDP)=1.3+/-0.2 muM, K(D)(GTP) approximately 200 muM and K(D)(GDPNP)>160 muM) as well as absence (K(D)(GDP)=1.9+/-0.3 muM, K(D)(GTP) 0.7+/-0.2 muM and K(D)(GDPNP) approximately 200 muM) of eRF1. From the present data we propose that (i) free eRF3 has a strong preference to bind GDP compared to GTP (ii) eRF3 in complex with eRF1 has much stronger affinity to GTP than free eRF3 (iii) eRF3 in complex with PABP has weak affinity to GTP (iv) eRF3 in complex with eRF1 does not have strong affinity to GDPNP, implying that GDPNP is a poor analogue of GTP for eRF3 binding.

GTP Phosphohydrolases↗
PubMed2005

Streptococcus rattus strain BHT produces both a class I two-component lantibiotic and a class II bacteriocin.

Streptococcus rattus strain BHT is a species representative and strong bacteriocin producer. Here we report that S. rattus BHT produces two quite different types of bacteriocin activity, named BHT-A and BHT-B. The two bacteriocins were purified and analysed for activity and by MALDI-TOF mass spectrophotometry. BHT-A was found to be a variant of the two-component lantibiotic, Smb. BHT-B is a non-modified 5195Da peptide with some similarity to the tryptophan-rich Staphylococcus aureus bacteriocin, aureocin A53. Six S. rattus and two S. mutans strains were found to contain both the BHT-A and BHT-B genetic loci.

Amino Acid Sequence↗
PubMed2004

Selective regulation of class I and class II histone deacetylases expression by inhibitors of histone deacetylases in cultured mouse neural cells.

The expression of 10 histone deacetylases (HDAC1-10) mRNAs in mouse neuroblastoma Neuro-2a and microglia N9 cell cultures after treatment by inhibitors of HDACs, sodium butyrate and trichostatin A was studied to elucidate whether HDAC inhibitors affect the gene expression of HDACs themselves. Northern blot analysis demonstrated two- to four-fold elevated levels of mRNAs for HDAC1, -3, -5, and -6 after drug treatment in comparison with untreated cells, while mRNA levels for HDAC2 and -7 did not change significantly. In both Neuro-2a and N9 cells the highest increase was observed for HDAC5 and -6 mRNA, whereas, HDAC4 had a prominent increase in mRNA levels after drug treatment only in N9 microglia cell line but not in Neuro-2a. Immunocytochemical examination confirmed that changes in protein levels of HDACs were similar to changes in their mRNA levels. There exists an auto-regulatory feedback loop to the expression levels of several HDACs after inhibition of their biochemical activity, adding several HDAC genes to the list of genes regulated by HDAC inhibitors.

Animals↗
PubMed2000

Shifts in the affinity distribution of one class of seven-transmembrane receptors by activation of a separate class of seven-transmembrane receptors.

We have demonstrated previously that activation of thrombin receptors causes increased Galpha(q) coupling to thromboxane A(2) receptors and increased thromboxane A(2) receptor ligand affinity. These results led to the hypothesis that thrombin receptor activation stimulates Galpha(q) redistribution to thromboxane A(2) receptors, thereby shifting them to a higher affinity state. The present study investigated three questions regarding this inter-receptor signaling phenomenon: (i) does activation of thrombin receptors cause a redistribution of thromboxane A(2) receptor subpopulations; (ii) does inter-receptor signaling require that participating receptors couple to the same family of G-protein alpha-subunits; and (iii) does inter-receptor signaling occur in cell types other than platelets? It was found that thrombin receptor activation caused a shift in the thromboxane A(2) receptor binding data from a one-site model to a two-site model (K(i) = 0.5 microM vs K(i) = 10 nM and 1.1 microM for the antagonist 4-[2-[[(4-chlorophenyl)sulfonyl]amino]ethyl]benzeneacetic acid (BM13. 505) and K(i) = 2.5 microM vs K(i) = 29.5 nM and 2.6 microM for the agonist 9,11-dideoxy-9alpha,11alpha-methanoepoxy prostaglandin F(2alpha) (U46619). It also was found that activation of prostaglandin D(2) receptors also caused a shift of prostacyclin receptor binding data from a one-site model (IC(50) = 10.1 nM) to a two-site model (IC(50) = 3.3 and 12.5 nM). The physiological manifestation of this inter-receptor signaling between prostacyclin and prostaglandin D(2) receptors was a synergistic inhibition of human platelet aggregation. Finally, the present results established that activation of endothelial cell thrombin receptors shifts thromboxane A(2) receptor affinity from K(i) = 0.8 microM (control) to K(i) = 0.2 microM (thrombin receptor-activating peptide), indicating that cells other than platelets have the capability to signal between seven-transmembrane receptors.

Blood Platelets↗
PubMedDate not supplied

The interaction of two classes of nuclear vesicles is induced by the dissociation of soluble proteins from one class of vesicles.

The regulatory mechanism of fusion steps in nuclear envelope assembly was studied in vitro using cell-free extracts of Xenopus eggs. The nuclear envelope is formed only around the chromatin at the end of mitosis. Two kinds of vesicles are required for nuclear envelope assembly (J. Cell Biol. 112 (1991) 545). Light vesicles (LVs) have the chromatin-binding activity, but cannot fuse solely. On the other hand, heavy vesicles (HVs) neither bind to the chromatin nor LVs, but are needed for the fusion event. Therefore, the association of HVs with LVs that bind to the chromatin is required at a first step during the fusion of vesicles. We found that salt-treated HVs inhibited the binding of LVs to the chromatin. In addition, when salt-treated HVs were pretreated with the proteins in the residue of salt-treatment of HVs, LVs recovered the chromatin-binding activity. In contrast, salt-treatment of LVs did not influence the binding of LVs with chromatin. By using a fluorescence microscopy assay, we showed directly that salt-treated HVs associated with LVs or salt-treated LVs, but HVs did not. These results suggest that soluble mask proteins on HVs keep the two distinct vesicles separate. We propose that the dissociation of mask protein on HVs allows HVs to bind with LVs that are located on the chromatin, subsequently the fusion of each vesicle occurs and the nuclear envelope is formed.

Animals↗
PubMed1999

6-(1-Hydroxyalkyl)penam sulfone derivatives as inhibitors of class A and class C beta-lactamases I.

Five 6-(1-hydroxyalkyl)penam sulfone derivatives and two 6-(hydroxymethyl)penams were synthesized for beta-lactamase inhibitor screens. The substituent effects and stereochemical requirements of 6alpha- and 6beta-(1-hydroxyalkyl) groups for the biological activity of penam sulfone derivatives were investigated. Of these substituents, only the 6beta-hydroxymethyl group of 15 improved the activity of sulbactam against both TEM-1 and AmpC beta-lactamases. The sulfone moiety is required for the enhancement of the beta-lactamase inhibitory activity. 6Beta-hydroxymethylsulbactam (15) was able to restore the activity of piperacillin in vitro and in vivo against various beta-lactamase producing microorganisms.

Animals↗