9,810 research outputs found
Single-molecule studies of unconventional motor protein myosin VI
No full textMyosin VI is one of the myosin superfamily members that are actin-based molecular motors. It has received special attention due to its distinct features as compared to other myosins, such as its opposite directionality and a much larger step size than expected given the length of its “leg”.
This dissertation presents the author‟s graduate work of several single-molecule studies on myosin VI. Special attention was paid to some of myosin VI‟s tail domains that consist of proximal tail (PT), medial tail (MT), distal tail (DT) domains and cargo-binding domain (CBD).
The functional form of myosin VI in cells is still under debate. Although full length myosin VI proteins in cytosolic extracts of cells were monomers from earlier studies, there are several reasons why it is now believed that myosin VI could exist as a dimer. If this is true and dimerization occurs, the next logical question would be which parts of myosin VI are dimerization regions? One model claimed that the CBD is the sole dimerization region. A competing model claimed that there must be another region that could be involved in dimerization, based on their observation that a construct without the CBD could still dimerize.
Our single-molecule experiment with progressively truncated myosin VI constructs showed that the MT domain is a dimerization region, supporting the latter model. Additional single-molecule experiments and molecular dynamics (MD) simulation done with our collaborators suggest that electrostatic salt bridges formed between positive and negative amino acid residues are mainly responsible for the MT domain dimerization.
After resolving this, we are left with another important question which is how myosin VI can take such a large step. Recent crystal structure showed that one of the tail domains preceding the MT domain, called the PT domain, is a three-helix bundle. The most easily conceivable way might be an unfolding of the three-helix bundle upon dimerization, allowing the protein to stretch and reach a larger distance. The single-molecule stepping data with mutant full-length construct that lacks two helices out of three in the PT domain tell that it is indeed the case.
In this dissertation, more details of myosin VI PT/MT domain experiments will be explored along with background information on the single-molecule experiment methods used in these studies.Item withdrawn by Mark Zulauf ([email protected]) on 2011-04-07T13:00:38Z
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University of Illinois Theses & Dissertations (ID: 1)
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University of Illinois Dissertations and Theses (ID: 204)
Dissertations and Theses - Physics (ID: 445)
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Resistance to CDK7 inhibitors directed by acquired mutation of a conserved residue in cancer cells
No full textCDK7 has emerged as a cancer target because of its pivotal roles in cell cycle progression and transcription. Several CDK7 inhibitors (CDK7i) are now in clinical evaluation. Identifying patients most likely to respond to treatment and early detection of tumour evolution towards resistance are necessary for optimal implementation of cancer therapies. Continuous culturing of prostate cancer cells with Samuraciclib, a non-covalent ATP-competitive CDK7i, led to outgrowth of resistant cells. These were characterised by the acquisition of a single base change in the CDK7 gene, Asp97 to Asn (D97N). Mutant cells were resistant to other non-covalent CDK7i but remained sensitive to covalent CDK7i. Cryo-EM structure and kinase ligand affinity determinations revealed reduced affinity of the CDK7-D97N mutant for non-covalent CDK7i. Remarkably, Asp97 is absolutely conserved in human CDKs, inferring its importance for the activities of all CDKs. Consistent with this, mutation of the homologous residue in CDK12 (D819N) or CDK4 (D99N) promoted resistance to drugs that inhibit these CDKs. Our findings reveal a general mechanism for acquired resistance with obvious implications for patients treated with CDK inhibitors
High-resolution cryo-EM of the human CDK-activating kinase for structure-based drug design
No full textBending dynamics of semi-flexible particles in turbulent flows
No full textWe study the Lagrangian dynamics of semi-flexible particles in laminar as well as in homogeneous and isotropic turbulent flows by means of analytically solvable stochastic models and direct numerical simulations. The statistics of the bending angle is qualitatively different in laminar and turbulent flows and exhibits a strong dependence on the topology of the velocity field. In particular, in two-dimensional turbulence, particles are either found in a fully extended or in a fully folded configuration; in three dimensions, the predominant configuration is the fully extended one
Vi Kowalchuk
No full textPhotograph - Vi Kowalchuk, member of the Book Sub-Committee, part of the Town of Athabasca 75th Anniversary Committee, Athabasca, Alberta. The Book Sub Committee produced the book "Athabasca Landing: An Illustrated History
Franklin Delano Roosevelt driving King George VI and Queen to Top Cottage, June 11, 1939
No full textFranklin Delano Roosevelt driving King George VI and Queen to Top Cottage, June 11, 1939, b&w. Label on back reads:Franklin Delano Roosevelt driving King & Queen to Top Cottage June 11, 1939, Betsy Cushing Roosevelt Betsy Cushing Roosevelt in passenger\u27s seat. She was the ex-wife of James Roosevelt (the eldest son of President Franklin D. Roosevelt (Roosevelt was president from 1933–1945.) This set of roosevelt photos are from Jean Ed. Smith\u27s files and papers used for his book on Franklin Delano Roosevelt.https://mds.marshall.edu/jean_smith_smith_papers/1048/thumbnail.jp
Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc
No full textWith the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in dichromate and sulfuric acid solution with different dipping times. The Cr(III) treatments were carried out in two commercial solutions (A and B). The thickness of the coatings was measured using ellipsometry. The morphologies and the compositions of the treated zinc have been studied by means of SEM, AFM, AES, FTIR and XPS. The drying temperature influence on the corrosion performance of the Cr(VI)âtreated zinc has been investigated. The Volta potential in treated and untreated areas has been measured using scanning Kelvin probe (SKP) and SKPFM. The corrosion behavior of the Cr(VI) and Cr(III) treated zinc has been investigated using polarization, electrochemical impedance measurements (EIS), and salt spray tests. Both Cr(VI) and Cr(III) species were detected by XPS in the outermost layer of the Cr(VI) coatings, while no Cr(VI) species was found in the Cr(III) coatings. AES depth profile results show that chromium oxides are the main components in the Cr(VI) coatings. Zinc oxide is mainly located at the chromium oxides / zinc interface. The Cr(III) coating is a mixture of chromium oxides and zinc oxide. Both the Cr(VI) and the Cr(III) treatments can supply corrosion protection to zinc. The corrosion resistance of the Cr(III)-B coating is greater than that of the Cr(III)-A coating. However, the inhibition of the corrosion of zinc by Cr(VI) coating is more effective than by the Cr(III) coatings. The inhibition of the corrosion of zinc by the Cr(VI) and the Cr(III) treatments is discussed, and future research topics are suggested.Mechanical, Maritime and Materials Engineerin
Xây dựng thang đo hành vi công dân tổ chức của nhân viên trong ngành khách sạn theo mô hình 3 chân (a three-leg model)
No full textIn the hospitality industry, the job characteristics of frontline employees are distinctively characterized by high levels of interaction while serving customers. In addition to organizational citizenship behavior directed towards colleagues and the organization, organizational citizenship behavior oriented towards customers significantly enhances positive customer experiences, which is a core factor contributing to the enterprise’s success. This study applies a three-leg model to develop a scale for measuring employees’ organizational citizenship behavior directly serving customers in the Danang City, Vietnam, hotel industry. The author employs a qualitative research method to gain deeper insights into the scale; subsequently, quantitative research is utilized to evaluate the scale. The research findings indicate that the three-leg model achieves a high level of compatibility, wherein the organizational citizenship behavior of hotel employees can be measured through 18 observed variables across three aspects: organizational citizenship behavior directed towards the organization (06 items), organizational citizenship behavior directed towards colleagues (06 items), and organizational citizenship behavior directed towards customers (06 items).Với ngành khách sạn, đặc điểm công việc của nhân viên tuyến đầu mang tính riêng biệt bởi dịch vụ đòi hỏi từ sự tương tác cao giữa khách hàng và nhân viên. Bên cạnh hành vi công dân tổ chức hướng đến đồng nghiệp và tổ chức, hành vi công dân tổ chức hướng đến khách hàng có ảnh hưởng đáng kể đến việc nâng cao trải nghiệm tích cực của khách hàng, là nhân tố cốt lõi đem lại hình ảnh thương hiệu cho khách sạn. Nghiên cứu này vận dụng mô hình 3 chân (a three-leg model) để xây dựng thang đo hành vi công dân tổ chức của nhân viên trong bối cảnh ngành khách sạn tại thành phố Đà Nẵng, Việt Nam. Để có những hiểu biết rõ ràng và thấu đáo hơn về thang đo, tác giả sử dụng phương pháp nghiên cứu định tính; tiếp theo, sử dụng nghiên cứu định lượng nhằm đánh giá thang đo. Kết quả nghiên cứu cho thấy mô hình 3 chân đạt được sự tương thích cao, trong đó hành vi công dân tổ chức của nhân viên trong ngành khách sạn có thể đo lường qua 18 mục hỏi ở 03 khía cạnh là hành vi công dân tổ chức hướng đến tổ chức (06 mục hỏi), hành vi công dân tổ chức hướng đến đồng nghiệp (06 mục hỏi) và hành vi công dân tổ chức hướng đến khách hàng (06 mục hỏi)
High-resolution cryo-EM of the human CDK-activating kinase for structure-based drug design
No full textAbstract Rational design of next-generation therapeutics can be facilitated by high-resolution structures of drug targets bound to small-molecule inhibitors. However, application of structure-based methods to macromolecules refractory to crystallization has been hampered by the often-limiting resolution and throughput of cryogenic electron microscopy (cryo-EM). Here, we use high-resolution cryo-EM to determine structures of the CDK-activating kinase, a master regulator of cell growth and division, in its free and nucleotide-bound states and in complex with 15 inhibitors at up to 1.8 Å resolution. Our structures provide detailed insight into inhibitor interactions and networks of water molecules in the active site of cyclin-dependent kinase 7 and provide insights into the mechanisms contributing to inhibitor selectivity, thereby providing the basis for rational design of next-generation therapeutics. These results establish a methodological framework for the use of high-resolution cryo-EM in structure-based drug design
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