Sec translocon is the major machinery for protein translocation in E.coli including SecYEG, SecA and other Sec proteins. It is generally assumed that during translocation process, SecYEG serves as a protein-conducting channel and transports the protein across membranes by using SecA ATPase as driving force. However, previous work suggested that protein translocation can occur without SecYEG. In order to understand the role of SecA in this SecYEG-independent process, we use voltage clamp recording as a tool to study the ionic activity of SecA-dependent protein-conducting channel. In a major deviation from the conventional view, we found that SecA alone is sufficient to promote the channel activity with liposomes made of E.coli phospholipids in both whole cell recording in the oocytes and in the single channel recording with patch clamp. The activity is strictly dependent on the presence of functional SecA, including those from different species of bacteria. However, this SecA-alone dependent channel activity is less efficient compared to the membranes containing SecYEG. Furthermore, the channel activity loses the signal peptide specificity. Addition of purified SecYEG restores the signal peptide specificity as well as the efficiency. This channel activity is more sensitive to SecA-specific inhibitors compared with membranes containing wild-type SecYEG but is less sensitive to membranes containing suppressor proteins. This is the first time it has been shown that SecA binds to lipid low-affinity site and functions as a protein-conducting channel. To further characterize the structural roles of SecA as the core of the channel, we use several SecA variants to reconstitute with liposomes to determine the domains involved in forming functional channels. Using deletion truncated domains of 901 residues SecA and liposomes in the oocytes recordings, we identify two critical SecA domains for the formation of pore channel activity: with phospholipids alone, and for interacting with SecYEG to gain higher activity. These data provide fundamental understanding for the SecA-dependent protein –conducting channels. Our findings also suggest the possible evolution process on the protein translocation pathways from prokaryotes through eukaryotes.

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The master thesis deals with the analysis of the profitability of the sales channels of the Decodom company. The thesis primarily focuses on the Activity Based Costing technique for measuring the performance of the company sales channels. The main aim of the thesis is to analyse the informational ability of the costing system in the company and prepare and propose a cost model, based on the Activity Based Costing method. The goal is achieved by the analysis of the current state of the company, the proposal of a model based on the costs of activities and the proposal of a new cost model based on this method. The contribution of the sales channels in the form of a pilot project is evaluated in the thesis which is performed on a sample of the kitchen range of the Decoplan product line. The thesis is divided in to three parts: theoretical, practical and applied (pilot project). The contribution of the thesis is a new view of the profitability of the examined company and general conclusions from the research, which can potentially be used in companies with a similar business model.

Yes / Ion channels represent a large and growing family of target proteins regulated by gasotransmitters such as nitric oxide, carbon monoxide and, as described more recently, hydrogen sulfide. Indeed, many of the biological actions of these gases can be accounted for by their ability to modulate ion channel activity. Here, we report recent evidence that H2S is a modulator of low voltage-activated T-type Ca2+ channels, and discriminates between the different subtypes of T-type Ca2+ channel in that it selectively modulates Cav3.2, whilst Cav3.1 and Cav3.3 are unaffected. At high concentrations, H2S augments Cav3.2 currents, an observation which has led to the suggestion that H2S exerts its pro-nociceptive effects via this channel, since Cav3.2 plays a central role in sensory nerve excitability. However, at more physiological concentrations, H2S is seen to inhibit Cav3.2. This inhibitory action requires the presence of the redox-sensitive, extracellular region of the channel which is responsible for tonic metal ion binding and which particularly distinguishes this channel isoform from Cav3.1 and 3.3. Further studies indicate that H2S may act in a novel manner to alter channel activity by potentiating the zinc sensitivity/affinity of this binding site. This review discusses the different reports of H2S modulation of T-type Ca2+ channels, and how such varying effects may impact on nociception given the role of this channel in sensory activity. This subject remains controversial, and future studies are required before the impact of T-type Ca2+ channel modulation by H2S might be exploited as a novel approach to pain management. / This work was supported by grants from the British Heart Foundation, the Medical Research Council, and the Hebei Medical University

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23065号 / 医博第4692号 / 新制||医||1049(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 村川 泰裕, 教授 平井 豊博, 教授 小川 誠司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM