Heterogeneity in Kinesin function
The kinesin family proteins are often studied as prototypical molecular motors; a deeper understanding of them can illuminate regulation of intracellular transport. It is typically assumed that they function identically. Here we find that this assumption of homogeneous function appears incorrect: variation among motors’ velocities in vivo and in vitro is larger than the stochastic variation expected for an ensemble of ‘identical" motors. When moving on microtubules, slow and fast motors are persistently slow, and fast, respectively. We develop theory that provides quantitative criteria to determine whether the observed...
Source: Traffic - July 21, 2017 Category: Research Authors: Babu J N Reddy, Suvranta Tripathy, Michael Vershinin, Marvin Tanenbaum, Jing Xu, Michelle Mattson ‐Hoss, Karim Arabi, Dail Chapman, Tory Doolin, Changbong Hyeon, Steven P. Gross Tags: ORIGINAL ARTICLE Source Type: research
Two novel effectors of trafficking and maturation of the yeast plasma membrane H+ ‐ATPase
ABSTRACT
The endoplasmic reticulum (ER) is the entry site of proteins into the endomembrane system. Proteins exit the ER via COPII vesicles in a selective manner, mediated either by direct interaction with the COPII coat or aided by cargo receptors. Despite the fundamental role of such receptors in protein sorting, only a few have been identified. To further define the machinery that packages secretory cargo and targets proteins from the ER to Golgi membranes, we used multiple systematic approaches, which revealed two uncharacterized proteins that mediate the trafficking and maturation of Pma1, the essential yeast plasma m...
Source: Traffic - July 20, 2017 Category: Research Authors: Yosef Geva, Jonathan Crissman, Eric C. Arakel, Natalia G ómez‐Navarro, Silvia G. Chuartzman, Kyle R. Stahmer, Blanche Schwappach, Elizabeth A. Miller, Maya Schuldiner Tags: ORIGINAL ARTICLE Source Type: research
Issue Information
(Source: Traffic)
Source: Traffic - July 12, 2017 Category: Research Tags: ISSUE INFORMATION Source Type: research
Sorting without a Golgi complex
Abstract
The ER‐Golgi‐target organelle route is one of the most studied events and has fascinated researchers for years. However, the conservative mechanism of protein sorting and delivery is now being challenged by the finding of unconventional pathways driving protein sorting and transport. Protozoa parasites are being rediscovered as good models for analyzing alternative targeting pathways, associated with their ability to adapt to diverse environments and hosts. Here, we have gathered all the available information about secretory protein trafficking in Giardia lamblia, with a focus on how this protozoan parasite is...
Source: Traffic - July 11, 2017 Category: Research Authors: Maria C. Touz, Nahuel Zamponi Tags: REVIEW Source Type: research
The ER is the sorting core facility in the Golgi ‐lacking protozoan Giardia lamblia
ABSTRACT
Our understanding of protein and lipid trafficking in eukaryotic cells has been challenged by the finding of different forms of compartmentalization and cargo processing in protozoan parasites. Here, we show that, in the absence of a Golgi compartment in Giardia, proteins destined for secretion are directly sorted and packaged at specialized ER regions enriched in COPII coatomer complexes and ceramide. We also demonstrated that ER‐resident proteins are retained at the ER by the action of a KDEL receptor, which, in contrast to other eukaryotic KDEL receptors, showed no interorganellar dynamic but instead acts spe...
Source: Traffic - July 11, 2017 Category: Research Authors: Nahuel Zamponi, Emiliano Zamponi, Gonzalo F. Mayol, Adriana Lanfredi ‐Rangel, Staffan G. Svärd, María C. Touz Tags: ORIGINAL ARTICLE Source Type: research
Transport of the alpha subunit of the L ‐type calcium channel through the sarcoplasmic reticulum occurs prior to localization to triads and requires the beta subunit but not Stac3 in skeletal muscles
Abstract
Contraction of skeletal muscle is initiated by excitation‐contraction (EC) coupling during which membrane voltage is transduced to intracellular Ca2+ release. EC coupling requires dihydropyridine receptors (DHPR) located at triads, which are junctions between the transverse (T) tubule and SR membranes, that sense membrane depolarization in the T tubule membrane. Reduced EC coupling is associated with ageing, and disruptions of EC coupling result in congenital myopathies for which there are few therapies. The precise localization of DHPRs to triads is critical for EC coupling, yet trafficking of the DHPR to triad...
Source: Traffic - July 1, 2017 Category: Research Authors: Jeremy W. Linsley, I ‐Uen Hsu, Wenjai Wang, John Y. Kuwada Tags: ORIGINAL ARTICLE Source Type: research
Structure and evolution of ENTH and VHS/ENTH ‐like domains in tepsin
Abstract
Tepsin is currently the only accessory trafficking protein identified in adaptor‐related protein 4 (AP4) coated vesicles originating at the trans‐Golgi network (TGN). The molecular basis for interactions between AP4 subunits and motifs in the tepsin C‐terminus have been characterized, but the biological role of tepsin remains unknown. We determined X‐ray crystal structures of the tepsin ENTH and VHS/ENTH‐like domains. Our data reveal unexpected structural features that suggest key functional differences between these and similar domains in other trafficking proteins. The tepsin ENTH domain lacks helix0, ...
Source: Traffic - July 1, 2017 Category: Research Authors: Tara L. Archuleta, Meredith N. Frazier, Anderson E. Monken, Amy K. Kendall, Joel Harp, Airlie J. McCoy, Nicole Creanza, Lauren P. Jackson Tags: ORIGINAL ARTICLE Source Type: research
Sorting nexin 27 interactome in T ‐lymphocytes identifies zona occludens‐2 dynamic redistribution at the immune synapse
This study broadens our knowledge of SNX27 function in T lymphocytes, and suggests that pathways that delimit polarized structures in nervous and epithelial systems also participate in IS regulation.
The role of sorting nexin 27 (SNX27) in the recycling of PSD95, Dlg1, ZO‐1 (PDZ)‐interacting neuronal proteins has been widely studied. In T lymphocytes, SNX27 localizes to the immune synapse (IS) where its function remains poorly understood. Using a proteomic strategy, we identified SNX27 PDZ‐dependent and ‐independent interactome in IS‐forming T cells. We showed that SNX27 participates in the dynamics of zona occ...
Source: Traffic - June 29, 2017 Category: Research Authors: Mar ía Tello‐Lafoz, Gonzalo Martínez‐Martínez, Cristina Rodríguez‐Rodríguez, Juan Pablo Albar, Morgan Huse, Severine Gharbi, Isabel Merida Tags: ORIGINAL ARTICLE Source Type: research
Vaccinia virus proteins A36 and F12/E2 show strong preferences for different kinesin light chain isoforms
Vaccinia virus (VACV) utilizes microtubule‐mediated trafficking at several stages of its life cycle, of which virus egress is the most intensely studied. During egress VACV proteins A36, F12 and E2 are involved in kinesin‐1 interactions; however, the roles of these proteins remain poorly understood. A36 forms a direct link between virions and kinesin‐1, yet in its absence VACV egress still occurs on microtubules. During a co‐immunoprecipitation screen to seek an alternative link between virions and kinesin, A36 was found to bind isoform KLC1 rather than KLC2. The F12/E2 complex associates preferentially with the C...
Source: Traffic - June 27, 2017 Category: Research Authors: William N.D. Gao, David C.J. Carpentier, Helen A. Ewles, Stacey ‐Ann Lee, Geoffrey L. Smith Tags: ORIGINAL ARTICLE Source Type: research
The Arl3 and Arl1 GTPase cooperates with Cog8 to regulate selective autophagy via Atg9 trafficking
In this study, we demonstrate that Arl3‐Arl1 small GTPase cascade cooperates with the subunit of COG complex to control Cvt pathway but not non‐selective autophagy. The yeast strains with dysfunction of Arl3‐Arl1 cascade and COG complex accumulate Atg9 at the late Golgi in nutrient‐rich condition, thereby causing the defect of Cvt pathway. Thus, two Golgi‐endosomal traffic components coordinately regulate the Cvt pathway by regulating Atg9 trafficking at the Golgi. (Source: Traffic)
Source: Traffic - June 19, 2017 Category: Research Authors: I ‐Hao Wang, Yi‐Jie Chen, Jia‐Wei Hsu, Fang‐Jen S. Lee Tags: ORIGINAL ARTICLE Source Type: research
The big and intricate dreams of little organelles: Embracing complexity in the study of membrane traffic
Abstract
Compartmentalization of eukaryotic cells into dynamic organelles that exchange material through regulated membrane traffic governs virtually every aspect of cellular physiology including signal transduction, metabolism and transcription. Much has been revealed about the molecular mechanisms that control organelle dynamics and membrane traffic and how these processes are regulated by metabolic, physical, and chemical cues. From this emerges the understanding of the integration of specific organellar phenomena within complex, multiscale, and non‐linear regulatory networks. In this review, we discuss systematic app...
Source: Traffic - June 16, 2017 Category: Research Authors: Allen P. Liu, Roberto J. Botelho, Costin N. Antonescu Tags: REVIEW Source Type: research
Erratum
(Source: Traffic)
Source: Traffic - June 8, 2017 Category: Research Authors: V íctor Hugo Cornejo, Alejandro Luarte, Andrés Couve Tags: ERRATUM Source Type: research
Issue Information
(Source: Traffic)
Source: Traffic - June 8, 2017 Category: Research Tags: ISSUE INFORMATION Source Type: research
The big and intricate dreams of little organselles: Embracing complexity in the study of membrane traffic
Abstract
Compartmentalization of eukaryotic cells into dynamic organelles that exchange material through regulated membrane traffic governs virtually every aspect of cellular physiology including signal transduction, metabolism and transcription. Much has been revealed about the molecular mechanisms that control organelle dynamics and membrane traffic and how these processes are regulated by metabolic, physical, and chemical cues. From this emerges the understanding of the integration of specific organellar phenomena within complex, multiscale, and non‐linear regulatory networks. In this review, we discuss systematic app...
Source: Traffic - June 1, 2017 Category: Research Authors: Allen P. Liu, Roberto J. Botelho, Costin N. Antonescu Tags: REVIEW Source Type: research
Oxysterol ‐binding protein recruitment and activity at the endoplasmic reticulum‐Golgi interface are independent of Sac1
Oxysterol‐binding protein (OSBP) localizes to endoplasmic reticulum (ER)‐Golgi contact sites where it transports cholesterol and phosphatidylinositol 4‐phosphate (PI‐4P), and activates lipid transport and biosynthetic activities. The PI‐4P phosphatase Sac1 cycles between the ER and Golgi apparatus where it potentially regulates OSBP activity. Here we examined whether the ER‐Golgi distribution of endogenous or ectopically expressed Sac1 influences OSBP activity. OSBP and Sac1 co‐localized at apparent ER‐Golgi contact sites in response to 25‐hydroxycholesterol (25OH), cholesterol depletion and p38 MAPK inhi...
Source: Traffic - May 31, 2017 Category: Research Authors: Mark Charman, Asako Goto, Neale D. Ridgway Tags: ORIGINAL ARTICLE Source Type: research
