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Cell Science at a Glance 4375 CELL SCIENCE AT A GLANCE 4375 The endocytosis compartment or prevacuole) by means of pathways. Mammalian proteins are in carrier vesicles or through a ‘maturation’ shown in red, and yeast proteins are machinery process (a change in biochemical shown in green. Where the mammalian Alexander Sorkin composition and morphology). Carrier and yeast protein have the same name, vesicles and late endosomes often this is given in green (AP-3, Vps17p, Dept of Pharmacology, University of Colorado Health Science Center, 4200 E. 9th Ave, Denver, display a morphology typical of multi- 26p, 29p, 35p) or red (GGAs). CO 80262, USA vesicular bodies, which contain internal Organelles are labelled in blue, with the membrane structures. These structures exception of yeast-specific names, which In mammalian cells, cargo can be appear to be formed by invagination of are green. Protein-protein interaction endocytosed via clathrin-coated pits, the the endosomal membrane. Late (EH, Eps15 homology, PH, pleckstrin clathrin-independent pathway or endosomes either mature into lysosomes homology; SH3, SRC homology 3) caveolae. In yeast cells the morphology or transfer cargo to lysosomes through domains are indicated. Closest of the internalization step is not yet vesicular intermediates. The recycling mammalian and yeast homologs are defined. All internalization pathways compartment is responsible for delivery separated by a solidus (/). Mammalian lead to the appearance of cargo in the of the cargo back to the cell surface. The homologs of yeast proteins involved in peripheral early endosomes. Coated endosome/lysosome system can send to the internalization step are actin (Act1p), vesicles must be at least partially and receive cargo from the trans-Golgi calmodulin (Cmd1p), type I uncoated to fuse with early endosomes. network (TGN) via vesicular (unconventional) myosin (Myo5p); EH- Early endosomes then undergo intermediates. Routes of internalization containing proteins (Pan1p and End3p), homotypic fusion. From early and intracellular trafficking are shown amphyphysins (Rvs161p and Rvs167p), endosomes cargo is recycled back to the by black arrows and labelled in black. synaptojanin (Sjl1p), and the clathrin plasma membrane, sorted to the late heavy and light chains (Chc1p and recycling compartment or delivered to The figure shows the major proteins Clc1p, respectively). Proteins, for which late endosomes (the prelysosomal involved in regulation of endocytic biochemical, functional or genetic α µ σ Epsin RAL β? α µ σ β? RLIP76 EPS15/EPS15R EH Epsin Intersectin/Ese EH EH SH3 POB1/REPS Dynamin SH3 Syndapin Cargo Clathrin- coated pit Caveolae Ankyrin Actin Dynamin Internalization End3p Myo5p Dynamin Actin cytoskeleton? in yeast cells Pan1p Cmd1p Abp1p PPIs cytoskeleton yAP180 Rvs161p β-Arrestin Endophilins Dynamin Clathrin- Sjl1p Rvs167p S PH Act1p SH3 H Caveolin/VIP21 3 independent Rsp5p Srv2p S Amphiphysins H 3 Sla2p PtdIns(5)Ps α µ internalization Vrp1p Chc1p ?σ PtdInsPs β RAB5 Ent1p Clc1p VAMP1 Bee1p Ent2p VAMP2 Sla1p Akr1p Synaptojanin Scd5p Synaptotagmin Intersectin/Ese PPIs Auxilin, SCAMPs Arp2p α µ Hsp70 σ Arp3p CALM/ β? AP180 AP-2 Clathrin-coated Unconventional vesicle Early endosome myosins Clathrin Calmodulin Clathrin triskelion AnnexinVI ARF6 RHOD ARNO RAB15 Rcy1p t-SNARE Early Vti1p v-SNARE Vps45p endosome Fab1p VAMP3 SNAP-NSF Pep12p VAMP8 Syntaxin13 βCOP PtdIns(3)P EEA.1/Vac1p ps34p RAB5 GTP /V Rabex/Vps9p GTP RAB5 PI3kinase p235/PIKfyve,PIP5-kinase/ Rabaptin Ypt51p/ RAB4 Syntaxin 6 PtdIns(3)P Pt Vps2p Vps22p Vps5p PtdIns dIns Rabphilin Vps45p RAB7 (3 RAB5-GDI HRS/Vps27p ,5 Vps20p Vps35p )P Vps28p 2 Vps24p Vps36p RAB11 TSG101/Vps23p Vps4p Vps32p Recycling compartment VAMP7 Lysobisphosphatidic acid Syntaxin 8 Multi-vesicular bodies RAB9 TIP47 Late endosomes PACS Prevacuole Vps11p ARF1 Vps45p Vps16p GGAs Tlg2p SNX3/Grd19p Vps18p Syntaxin 6 Tlg1p Chc1p Vps33p Syntaxin 10 Syntaxin 11 Syntaxin 16 VAMP4 ARF1 Mvp1p Retromer: Synergin γ µ Vps1p σ SNX1-2/Vps5p EH β? Vps34p AP-1 Vps17p TG clathrin Vps26p Vam3p N Rabaptin Vps29p Vam7p Vps35p Vti1p Syntaxin 7 Vps52p Lysosome/vacuole Vps53p Vps54p µ δ σ AP-3 β? Vps39p Vps41p (See poster insert) 4376 CELL SCIENCE AT A GLANCE interactions have been demonstrated are polyphosphoinositides; PtdIns, membrane soluble NSF attachment shown in boxes. Each AP-1, AP-2 and phosphatidylinositol; PtdIns(3)P, PtdIns protein receptors. Vps, vacuolar protein AP-3 complex consists of four subunits: 3-phosphate; PtdIns(3,5)P2, PtdIns 3,5- sorting. β, µ and σ are highly homologous in all bisphosphate; PtdIns(5)Ps, PtdIns three complexes, whereas γ, α and δ are phosphates phosphorylated at position 5; Cell Science at a Glance on the Web specific for AP-1, AP-2 and AP-3, PtdInsPs, PtdIns(5)Ps in which the Electronic copies of the full-size poster respectively. β-arrestin can bind to phosphate has been removed from insert are available in the online version of clathrin and AP-2 and is involved in position 5. Other abbreviations: NSF, N- this article (see www.biologists.com/jcs). coated-pit recruitment of G-protein- ethylmaleimide-sensitive factor; v- and Files in several formats are provided and coupled receptors. Lipids: PPIs, t-SNARE, vesicular- and target- may be downloaded for use as slides..
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