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Thomas Martin

Bio: Thomas Martin is an academic researcher from University of California, San Francisco. The author has contributed to research in topics: Exocytosis & Medicine. The author has an hindex of 73, co-authored 242 publications receiving 15771 citations. Previous affiliations of Thomas Martin include Institut national de la recherche agronomique & University of Western Australia.


Papers
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Journal ArticleDOI
09 Mar 1995-Nature
TL;DR: The results indicate that lipid kinase-mediated phosphorylation is an important basis for ATP use in the exocytotic pathway.
Abstract: REGULATED fusion of secretory granules with the plasma membrane in secretory cells requires ATP, Ca2+ and cytosolic1-3 as well as membrane4 proteins. ATP-dependent steps in Ca2+-activated secretion from PC 12 cells require three cytosolic PEP proteins (priming in exocytosis proteins, PEP1–3)5,6, the identity of which will provide insights into the required ATP-using reactions. PEP3 was recently identified as phosphatidylinositol transfer protein (PtdlnsTP)6, and here we report that PEP1 consists of the type I phosphatidylinositol-4-phosphate 5-kinase (PtdlnsPSK). The roles of PEP3/PtdInsTP and PEP1/ PtdlnsPSK in sequential phosphoinositide recruitment and phosphorylation explains their synergistic activity in ATP-dependent priming. Moreover, inhibition of Ca2+-activated secretion by PtdIns(4,5)P2-specific antibodies and phospholipase C implies that 5-phosphorylated inositides play a novel, necessary role in the regulated secretory pathway. The results indicate that lipid kinase-mediated phosphorylation is an important basis for ATP use in the exocytotic pathway.

512 citations

Journal ArticleDOI
TL;DR: The CARITUDE-1 trial as discussed by the authors evaluated the safety and clinical activity of ciltacabtagene autoleucel (cilta-cel), a chimeric antigen receptor T-cell therapy with two B-cell maturation antigen-targeting single-domain antibodies.

494 citations

Journal ArticleDOI
TL;DR: Common themes of localized signal generation and the spatially localized recruitment of effector proteins appear to underlie mechanisms employed in signal transduction, cytoskeletal, and membrane trafficking events.
Abstract: Signaling roles for phosphoinositides that involve their regulated hydrolysis to generate second messengers have been well characterized. Recent work has revealed additional signaling roles for phosphoinositides that do not involve their hydrolysis. PtdIns 3-P, PtdIns 3,4,5-P3, and PtdIns 4,5-P2 function as site-specific signals on membranes that recruit and/or activate proteins for the assembly of spatially localized functional complexes. A large number of phosphoinositide-binding proteins have been identified as the potential effectors for phosphoinositide signals. Common themes of localized signal generation and the spatially localized recruitment of effector proteins appear to underlie mechanisms employed in signal transduction, cytoskeletal, and membrane trafficking events.

493 citations

Journal ArticleDOI
26 Jan 1990-Cell
TL;DR: It is proposed that combinatorial interactions between b polypeptides generate regulatory proteins that determine the developmental program of the fungus.

399 citations


Cited by
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Journal ArticleDOI
18 Jul 1986-Science
TL;DR: A novel role of this protein kinase system seems to give a logical basis for clarifying the biochemical mechanism of signal transduction, and to add a new dimension essential to the understanding of cell-to-cell communication.
Abstract: Protein kinase C, an enzyme that is activated by the receptor-mediated hydrolysis of inositol phospholipids, relays information in the form of a variety of extracellular signals across the membrane to regulate many Ca2+-dependent processes. At an early phase of cellular responses, the enzyme appears to have a dual effect, providing positive forward as well as negative feedback controls over various steps of its own and other signaling pathways, such as the receptors that are coupled to inositol phospholipid hydrolysis and those of some growth factors. In biological systems, a positive signal is frequently followed by immediate negative feedback regulation. Such a novel role of this protein kinase system seems to give a logical basis for clarifying the biochemical mechanism of signal transduction, and to add a new dimension essential to our understanding of cell-to-cell communication.

5,006 citations

Journal ArticleDOI
TL;DR: The evidence for this hypothesis, and the origins of the different kinetic phases of synaptic enhancement, as well as the interpretation of statistical changes in transmitter release and roles played by other factors such as alterations in presynaptic Ca(2+) influx or postsynaptic levels of [Ca(2+)]i are discussed.
Abstract: ▪ Abstract Synaptic transmission is a dynamic process. Postsynaptic responses wax and wane as presynaptic activity evolves. This prominent characteristic of chemical synaptic transmission is a crucial determinant of the response properties of synapses and, in turn, of the stimulus properties selected by neural networks and of the patterns of activity generated by those networks. This review focuses on synaptic changes that result from prior activity in the synapse under study, and is restricted to short-term effects that last for at most a few minutes. Forms of synaptic enhancement, such as facilitation, augmentation, and post-tetanic potentiation, are usually attributed to effects of a residual elevation in presynaptic [Ca2+]i, acting on one or more molecular targets that appear to be distinct from the secretory trigger responsible for fast exocytosis and phasic release of transmitter to single action potentials. We discuss the evidence for this hypothesis, and the origins of the different kinetic phases...

4,687 citations

Journal ArticleDOI
TL;DR: What is known about mammalian endocytic mechanisms is reviewed, with focus on the cellular proteins that control these events, and the functional relevance of distinctendocytic pathways is discussed.
Abstract: Endocytic mechanisms control the lipid and protein composition of the plasma membrane, thereby regulating how cells interact with their environments. Here, we review what is known about mammalian endocytic mechanisms, with focus on the cellular proteins that control these events. We discuss the well-studied clathrin-mediated endocytic mechanisms and dissect endocytic pathways that proceed independently of clathrin. These clathrin-independent pathways include the CLIC/GEEC endocytic pathway, arf6-dependent endocytosis, flotillin-dependent endocytosis, macropinocytosis, circular doral ruffles, phagocytosis, and trans-endocytosis. We also critically review the role of caveolae and caveolin1 in endocytosis. We highlight the roles of lipids, membrane curvature-modulating proteins, small G proteins, actin, and dynamin in endocytic pathways. We discuss the functional relevance of distinct endocytic pathways and emphasize the importance of studying these pathways to understand human disease processes.

2,685 citations

Journal ArticleDOI
TL;DR: Current analyses of genetic defects in Drosophila melanogaster, mice, and humans confirm most of these activities in vivo and identify additional processes that involve cell surface heparan sulfate proteoglycans.
Abstract: The heparan sulfate on the surface of all adherent cells modulates the actions of a large number of extracellular ligands. Members of both cell surface heparan sulfate proteoglycan families, the transmembrane syndecans and the glycosylphosphoinositide-linked glypicans, bind these ligands and enhance formation of their receptor-signaling complexes. These heparan sulfate proteoglycans also immobilize and regulate the turnover of ligands that act at the cell surface. The extracellular domains of these proteoglycans can be shed from the cell surface, generating soluble heparan sulfate proteoglycans that can inhibit interactions at the cell surface. Recent analyses of genetic defects in Drosophila melanogaster, mice, and humans confirm most of these activities in vivo and identify additional processes that involve cell surface heparan sulfate proteoglycans. This chapter focuses on the mechanisms underlying these activities and on the cellular functions that they regulate.

2,680 citations

Journal ArticleDOI
12 Oct 2006-Nature
TL;DR: Inositol phospholipids mediate acute responses, but also act as constitutive signals that help define organelle identity, and play a fundamental part in controlling membrane–cytosol interfaces.
Abstract: Inositol phospholipids have long been known to have an important regulatory role in cell physiology. The repertoire of cellular processes known to be directly or indirectly controlled by this class of lipids has now dramatically expanded. Through interactions mediated by their headgroups, which can be reversibly phosphorylated to generate seven species, phosphoinositides play a fundamental part in controlling membrane-cytosol interfaces. These lipids mediate acute responses, but also act as constitutive signals that help define organelle identity. Their functions, besides classical signal transduction at the cell surface, include regulation of membrane traffic, the cytoskeleton, nuclear events and the permeability and transport functions of membranes.

2,528 citations