Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The FtsH (HflB) protein of Escherichia coli is integrated into the membrane with two N-terminally located transmembrane segments, while its large cytoplasmic domain is homologous to the AAA family of ATPases. The previous studies on dominant negative ftsH mutants raised a possibility that FtsH functions in multimeric states. We found that FtsH was eluted at fractions corresponding to a larger molecular weight than expected from monomeric structure in size-exclusion chromatography. Moreover, treatment of membranes or their detergent extracts with a cross-linker, dithiobis(succinimidyl propionate), yielded cross-linked products of FtsH. To dissect possible FtsH complex, we constructed an FtsH derivative with c-Myc epitope at its C terminus (FtsH-His6-Myc). When membranes prepared from cells in which FtsH-His6-Myc was overproduced together with the normal FtsH were treated with the cross-linker, intact FtsH and in vitro degradation products of FtsH-His6-Myc without the tag were cross-linked with the tagged FtsH protein. Co-immunoprecipitation experiments confirmed the interaction between the FtsH molecules. To identify regions of FtsH required or sufficient for this interaction, we constructed chimeric proteins between FtsH and EnvZ, a protein with a similar topological arrangement, by exchanging their corresponding domains. We found that only the FtsH-EnvZ hybrid protein with an FtsH-derived membrane anchoring domain and an EnvZ-derived cytoplasmic domain caused a dominant ftsH phenotype and was cross-linked with FtsH. We suggest that the N-terminal transmembrane region of FtsH mediates directly the interaction between the FtsH subunits.
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PMID:FtsH, a membrane-bound ATPase, forms a complex in the cytoplasmic membrane of Escherichia coli. 755 11

Epidermal growth factor receptor (EGFR) is usually overexpressed in nasopharyngeal carcinoma (NPC). Our recent in vitro study has demonstrated that cetuximab (an antibody drug against EGFR) inhibits the growth of NPC cell lines, HK1 and HONE-1. The present study investigates the effect of cetuximab on protein expressions of NPC cell lines. NPC cells were cultured in the absence or presence of cetuximab at the IC50 concentrations (3 nM for HK1 and 0.3 nM for HONE-1) for 48 h, and total cell lysates were extracted. The cell lysates were then subjected to two-dimensional polyacrylamide gel electrophoresis (2D PAGE), and the 2D gel images were compared to discover the protein changes caused by cetuximab treatment. The common differentially expressed proteins in NPC cell lines were identified by peptide mass fingerprinting. We found that heat shock protein gp96 was down-regulated, while alpha-enolase, tumor suppressor protein maspin, and p97 valosin containing protein were up-regulated after cetuximab treatment. Reverse-transcription polymerase chain reaction (RT-PCR) analysis confirmed that the changes in protein levels of gp96, maspin, and p97 coincided with mRNA levels, indicating that these proteins were regulated at transcriptional levels. Up-regulation of gp96 has been observed in various cancers and reported to have tumor protective effects. P97 is a multifunctional AAA (ATPase associated with a variety of activities) protein and is involved in numerous cellular activities including membrane transport, protein folding, protein degradation, and cell division. Maspin has been shown to increase apoptosis, and block the growth, invasion, and metastatic properties of many tumors. The comparative tumor suppression effects of cetuximab and maspin suggest that cetuximab might exert its antitumor effects partly by up-regulation of maspin expression. The study also indicates that proteomic analysis is a promising approach to elucidate the functional mechanisms of anticancer drugs. Pharmacoproteomic study may also help to identify clinical responders for drug treatment and provide insight for new drug development.
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PMID:Pharmacoproteomics study of cetuximab in nasopharyngeal carcinoma. 1713 27