Gert Kreibich

Gert Kreibich

Research Professor, Department of Cell Biology

synthesis, assembly and sorting of membrane proteins, differentiation of rough and smoote ER domains, organelle biogenesis, bladder epithelium

Synthesis, Assembly and Sorting of Membrane Proteins Research Summary The endoplasmic reticulum (ER) plays a central role in the synthesis of a large number of proteins which are then distributed to different subcellular compartments. Polypeptides are inserted into ER membranes during the course of their elongation in membrane-bound ribosomes, cotranslationally modified and, when their synthesis is completed, they may form oligomeric complexes. Our research is concerned with the functional organization of ER membranes, the process of assembly of membrane proteins into oligomeric complexes, and the biogenetic relationship between the ER and other subcellular membrane systems. Of special interest are the components of the polypeptide translocation apparatus in the ER which are involved in signal sequence recognition, insertion, translocation and in the cotranslational processing of proteins synthesized in membrane bound polysomes. We have discovered two transmembrane glycoproteins, ribophorins I and II, which, together with membrane proteins that include 48 kD (OST48) and 12 kD (Dad1), form an oligomeric complex that functions in the cotranslational N-glycosylation of the growing nascent chains. Using biophysical approaches such as fluorescent recovery after photobleaching (FRAP), we have investigated mechanisms by which the membrane proteins forming the translocation apparatus are retained in the ER, while other membrane proteins exit from this organelle. We have found that microtubules that bind to the ER-specific membrane protein CLIMP-63 interfere with the lateral mobility of membrane bound polysomes in the lipid bilayer of ER membranes. (Supported by NSF) Related to our interest in the oligomerization of membrane proteins are studies on the assembly and the intracellular transport of four membrane proteins (uropakins Ia, Ib, II and III) that are expressed in the bladder epithelium (urothelium). These membrane proteins are made on membrane bound polysomes, and the co- and posttranslationally processed proteins accumulate in a post-Golgi compartment where they assemble into two dimensional crystals that have have the appearance of asymmetric unit membranes (AUMs). Eventually, these AUMs cover the whole surface of fusiform vesicles (FVs). These AUM storage organelles, that belong to the class of lysosome-related organelles, can fuse in a regulated fashion with the apical surface of urothelial cells. Our research is concerned with the elucidation of mechanisms that function in the delivery of these highly specialized membranes to the apical surface of the bladder epithelium, and in the regulation of endocytic processes that result in the degradation of AUMs. For these studies we use aside from ultrastructural, biochemical and molecular biology approaches also mouse strains that have specific genes deleted (Rab27b), or carry mutations that affect lysosome-related organelles and represent mouse models for Hermansky-Pudlack Syndrome. (Supported by NIH)

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New York, NY 10016

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Research Professor, Department of Cell Biology

Wankel, Bret; Ouyang, Jiangyong; Guo, Xuemei; Hadjiolova, Krassimira; Miller, Jeremy; Liao, Yi; Tham, Daniel Kai Long; Romih, Rok; Andrade, Leonardo R; Gumper, Iwona; Simon, Jean-Pierre; Sachdeva, Rakhee; Tolmachova, Tanya; Seabra, Miguel C; Fukuda, Mitsunori; Schaeren-Wiemers, Nicole; Hong, WanJin; Sabatini, David D; Wu, Xue-Ru; Kong, Xiangpeng; Kreibich, Gert; Rindler, Michael J; Sun, Tung-Tien

Molecular biology of the cell. 2016 May 15; 27(10):1621-1634

Vieira, Neide; Deng, Fang-Ming; Liang, Feng-Xia; Liao, Yi; Chang, Jennifer; Zhou, Ge; Zheng, Weiyue; Simon, Jean-Pierre; Ding, Mingxiao; Wu, Xue-Ru; Romih, Rok; Kreibich, Gert; Sun, Tung-Tien

PLoS one. 2014; 9(6):e99644-e99644e99644

Zhou, G; Liang, FX; Romih, R; Wang, Z; Liao, Y; Ghiso, J; Luque-Garcia, JL; Neubert, TA; Kreibich, G; Alonso, MA; Schaeren-Wiemers, N; Sun, TT

Molecular biology of the cell. 2012 Apr; 23(7):1354-1366

Guo, Xuemei; Tu, Liyu; Gumper, Iwona; Plesken, Heide; Novak, Edward K; Chintala, Sreenivasulu; Swank, Richard T; Pastores, Gregory; Torres, Paola; Izumi, Tetsuro; Sun, Tung-Tien; Sabatini, David D; Kreibich, Gert

Traffic. 2009 Sep; 10(9):1350-1361

Wu, Xue-Ru; Kong, Xiang-Peng; Pellicer, Angel; Kreibich, Gert; Sun, Tung-Tien

Kidney international. 2009 Jun; 75(11):1153-1165

Hu, Chih-Chi Andrew; Bachmann, Thomas; Zhou, Ge; Liang, Feng-Xia; Ghiso, Jorge; Kreibich, Gert; Sun, Tung-Tien

Biochemical journal. 2008 Sep 01; 414(2):195-203

Nikonov, Andrei V; Hauri, Hans-Peter; Lauring, Brett; Kreibich, Gert

Journal of cell science. 2007 Jul 01; 120(Pt 13):2248-2258

Tu, Liyu; Kong, Xiang-Peng; Sun, Tung-Tien; Kreibich, Gert

Journal of cell science. 2006 Dec 15; 119(Pt 24):5077-5086