scholarly journals The FTS-Hook-FHIP (FHF) complex interacts with AP-4 to mediate perinuclear distribution of AP-4 and its cargo ATG9A

2020 ◽  
Vol 31 (9) ◽  
pp. 963-979 ◽  
Author(s):  
Rafael Mattera ◽  
Chad D. Williamson ◽  
Xuefeng Ren ◽  
Juan S. Bonifacino
Keyword(s):  
Adaptor Protein ◽  
Accessory Factor ◽  
Transport Vesicles ◽  
Microtubule Motors ◽  
Perinuclear Area

In this study, we identify the dynein–dynactin adaptor FTS-Hook-FHIP (FHF) complex as an accessory factor for the TGN-associated adaptor protein 4 (AP-4) coat. We show that FHF is required for distribution of AP-4 and its cargo ATG9A to the perinuclear area, highlighting a novel mechanism for coupling of transport vesicles to microtubule motors.

scholarly journals S-Palmitoylation determines TMEM55B-dependent positioning of lysosomes

2021 ◽  
Author(s):  
Sönke Rudnik ◽  
Saskia Heybrock ◽  
Paul Saftig ◽  
Markus Damme
Keyword(s):  
Molecular Motors ◽  
Protein Complexes ◽  
Critical Role ◽  
Adaptor Protein ◽  
Retrograde Transport ◽  
Microtubule Motors ◽  
Lysosomal Sorting ◽  
Sorting Motif ◽  
Spatio Temporal

The spatio-temporal cellular distribution of lysosomes depends on active transport mainly driven by microtubule-motors such as kinesins and dynein. Different protein complexes attach these molecular motors to their vesicular cargo: TMEM55B, as an integral lysosomal membrane protein, is a component of such a complex mediating the retrograde transport of lysosomes by establishing an interaction with the cytosolic scaffold protein JIP4 and dynein/dynactin. Here we show that TMEM55B and its paralog TMEM55A are S-palmitoylated proteins and lipidated at multiple cysteine-residues. Mutation of all cysteines in TMEM55B prevents S-palmitoylation and causes the retention of the mutated protein in the Golgi-apparatus. Consequently, non-palmitoylated TMEM55B is no longer able to modulate lysosomal positioning and the perinuclear clustering of lysosomes. Additional mutagenesis of the dileucine-based lysosomal sorting motif in non-palmitoylated TMEM55B leads to partial missorting to the plasma membrane instead of retention in the Golgi, implicating a direct effect of S-palmitoylation on the adaptor-protein-dependent sorting of TMEM55B. Our data suggest a critical role of S-palmitoylation on the trafficking of TMEM55B and TMEM55B-dependent lysosomal positioning.

scholarly journals The adaptor protein AP-4 as a component of the clathrin coat machinery: a morphological study

2005 ◽  
Vol 385 (2) ◽  
pp. 503-510 ◽  
Author(s):  
Nicolas BAROIS ◽  
Oddmund BAKKE
Keyword(s):  
Golgi Complex ◽  
Intracellular Trafficking ◽  
Intracellular Localization ◽  
Adaptor Protein ◽  
Immunogold Labelling ◽  
Endocytic Pathway ◽  
Transport Vesicles ◽  
Cargo Proteins ◽  
The Difference ◽  
First Time

The four members of the AP (adaptor protein) family are heterotetrameric cytosolic complexes that are involved in the intracellular trafficking of cargo proteins between different organelles. They interact with motifs present in the cytoplasmic tails of their specific cargo proteins at different intracellular locations. While AP-1, AP-2 and AP-3 have been investigated extensively, very few studies have focused on the fourth member, AP-4. In the present study, we report on the intracellular localization of AP-4 in the MDCK (Madin–Darby canine kidney) and MelJuSo cell lines after immunogold labelling of ultrathin cryosections. We find that AP-4 is localized mainly in the Golgi complex, as well as on endosomes and transport vesicles. Interestingly, we show for the first time that AP-4 is localized with the clathrin coat machinery in the Golgi complex and in the endocytic pathway. Furthermore, we find that AP-4 is localized with the CI-MPR (cation-independent mannose 6-phosphate receptor), but not with the transferrin receptor, LAMP-2 (lysosomal-associated membrane protein-2) or invariant chain. The difference in morphology between CI-MPR/AP-4-positive vesicles and CI-MPR/AP-1-positive vesicles raises the possibility that AP-4 acts at a location different from that of AP-1 in the intracellular trafficking pathway of CI-MPR.

scholarly journals Interactions between Syntaxins Identify at Least Five SNARE Complexes within the Golgi/Prevacuolar System of the Arabidopsis Cell

2001 ◽  
Vol 12 (12) ◽  
pp. 3733-3743 ◽  
Author(s):  
Anton A. Sanderfoot ◽  
Valya Kovaleva ◽  
Diane C. Bassham ◽  
Natasha V. Raikhel
Keyword(s):  
Single Gene ◽  
Adaptor Protein ◽  
Gene Families ◽  
Snare Complex ◽  
Transport Vesicles ◽  
Protein Receptors ◽  
Member Gene ◽  
Model Plant Arabidopsis Thaliana ◽  
Prevacuolar Compartment ◽  
Golgi Network

The syntaxin family of soluble N-ethyl maleimide sensitive factor adaptor protein receptors (SNAREs) is known to play an important role in the fusion of transport vesicles with specific organelles. Twenty-four syntaxins are encoded in the genome of the model plant Arabidopsis thaliana. These 24 genes are found in 10 gene families and have been reclassified as syntaxins of plants (SYPs). Some of these gene families have been previously characterized, with the SYP2-type syntaxins being found in the prevacuolar compartment (PVC) and the SYP4-type syntaxins on thetrans-Golgi network (TGN). Here we report on two previously uncharacterized syntaxin groups. The SYP5 group is encoded by a two-member gene family, whereas SYP61 is a single gene. Both types of syntaxins are localized to multiple compartments of the endomembrane system, including the TGN and the PVC. These two groups of syntaxins form SNARE complexes with each other, and with other Arabidopsis SNAREs. On the TGN, SYP61 forms complexes with the SNARE VTI12 and either SYP41 or SYP42. SYP51 and SYP61 interact with each other and with VTI12, most likely also on the TGN. On the PVC, a SYP5-type syntaxin interacts specifically with a SYP2-type syntaxin, as well as the SNARE VTI11, forming a SNARE complex likely involved in TGN-to-PVC trafficking.

scholarly journals Adaptins

2001 ◽  
Vol 12 (10) ◽  
pp. 2907-2920 ◽  
Author(s):  
Markus Boehm ◽  
Juan S. Bonifacino
Keyword(s):  
Arabidopsis Thaliana ◽  
Intracellular Transport ◽  
Adaptor Protein ◽  
Fruit Fly ◽  
C Elegans ◽  
Transport Vesicles ◽  
Intron Structure ◽  
Related Proteins ◽  
Selection Of ◽  
Plant Arabidopsis Thaliana

Adaptins are subunits of adaptor protein (AP) complexes involved in the formation of intracellular transport vesicles and in the selection of cargo for incorporation into the vesicles. In this article, we report the results of a survey for adaptins from sequenced genomes including those of man, mouse, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, the plant Arabidopsis thaliana, and the yeasts, Saccharomyces cerevisiae andSchizosaccharomyces pombe. We find that humans, mice, and Arabidopsis thaliana have four AP complexes (AP-1, AP-2, AP-3, and AP-4), whereas D. melanogaster,C. elegans, S. cerevisiae, and S. pombe have only three (AP-1, AP-2, and AP-3). Additional diversification of AP complexes arises from the existence of adaptin isoforms encoded by distinct genes or resulting from alternative splicing of mRNAs. We complete the assignment of adaptins to AP complexes and provide information on the chromosomal localization, exon-intron structure, and pseudogenes for the different adaptins. In addition, we discuss the structural and evolutionary relationships of the adaptins and the genetic analyses of their function. Finally, we extend our survey to adaptin-related proteins such as the GGAs and stonins, which contain domains homologous to the adaptins.

scholarly journals Binding of cargo sorting signals to AP-1 enhances its association with ADP ribosylation factor 1–GTP

2008 ◽  
Vol 180 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Intaek Lee ◽  
Balraj Doray ◽  
Jennifer Govero ◽  
Stuart Kornfeld
Keyword(s):  
Adaptor Protein ◽  
Adenosine Diphosphate ◽  
Core Domain ◽  
Transport Vesicles ◽  
Sorting Signals ◽  
Stable Association ◽  
Golgi Network ◽  
Adp Ribosylation Factor ◽  
Prevailing View ◽  
Cargo Sorting

The adaptor protein AP-1 is the major coat protein involved in the formation of clathrin-coated vesicles at the trans-Golgi network. The prevailing view is that AP-1 recruitment involves coincident binding to multiple low-affinity sites comprising adenosine diphosphate ribosylation factor 1 (Arf-1)–guanosine triphosphate (GTP), cargo sorting signals, and phosphoinositides. We now show that binding of cargo signal peptides to AP-1 induces a conformational change in its core domain that greatly enhances its interaction with Arf-1–GTP. In addition, we provide evidence for cross talk between the dileucine and tyrosine binding sites within the AP-1 core domain such that binding of a cargo signal to one site facilitates binding to the other site. The stable association of AP-1 with Arf-1–GTP, which is induced by cargo signals, would serve to provide sufficient time for adaptor polymerization and clathrin recruitment while ensuring the packaging of cargo molecules into the forming transport vesicles.

scholarly journals Cargo Sorting at the trans-Golgi Network for Shunting into Specific Transport Routes: Role of Arf Small G Proteins and Adaptor Complexes

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 531 ◽  
Author(s):  
Jing Zhi Anson Tan ◽  
Paul Anthony Gleeson
Keyword(s):  
G Proteins ◽  
Adaptor Protein ◽  
Coat Proteins ◽  
Transport Pathway ◽  
Trans Golgi Network ◽  
Transport Vesicles ◽  
Different Populations ◽  
The Individual ◽  
Golgi Network ◽  
Small G Proteins

The trans-Golgi network (TGN) is responsible for selectively recruiting newly synthesized cargo into transport carriers for delivery to their appropriate destination. In addition, the TGN is responsible for receiving and recycling cargo from endosomes. The membrane organization of the TGN facilitates the sorting of cargoes into distinct populations of transport vesicles. There have been significant advances in defining the molecular mechanism involved in the recognition of membrane cargoes for recruitment into different populations of transport carriers. This machinery includes cargo adaptors of the adaptor protein (AP) complex family, and monomeric Golgi-localized γ ear-containing Arf-binding protein (GGA) family, small G proteins, coat proteins, as well as accessory factors to promote budding and fission of transport vesicles. Here, we review this literature with a particular focus on the transport pathway(s) mediated by the individual cargo adaptors and the cargo motifs recognized by these adaptors. Defects in these cargo adaptors lead to a wide variety of diseases.

scholarly journals HOPS Interacts with Apl5 at the Vacuole Membrane and Is Required for Consumption of AP-3 Transport Vesicles

2009 ◽  
Vol 20 (21) ◽  
pp. 4563-4574 ◽  
Author(s):  
Cortney G. Angers ◽  
Alexey J. Merz
Keyword(s):  
Fluorescence Microscopy ◽  
Protein Complexes ◽  
Adaptor Protein ◽  
Vesicle Budding ◽  
Vesicle Docking ◽  
Vacuole Membrane ◽  
Vesicle Traffic ◽  
Transport Vesicles ◽  
Evolutionarily Conserved ◽  
Curved Membranes

Adaptor protein complexes (APs) are evolutionarily conserved heterotetramers that couple cargo selection to the formation of highly curved membranes during vesicle budding. In Saccharomyces cerevisiae , AP-3 mediates vesicle traffic from the late Golgi to the vacuolar lysosome. The HOPS subunit Vps41 is one of the few proteins reported to have a specific role in AP-3 traffic, yet its function remains undefined. We now show that although the AP-3 δ subunit, Apl5, binds Vps41 directly, this interaction occurs preferentially within the context of the HOPS docking complex. Fluorescence microscopy indicates that Vps41 and other HOPS subunits do not detectably colocalize with AP-3 at the late Golgi or on post-Golgi (Sec7-negative) vesicles. Vps41 and HOPS do, however, transiently colocalize with AP-3 vesicles when these vesicles dock at the vacuole membrane. In cells with mutations in HOPS subunits or the vacuole SNARE Vam3, AP-3 shifts from the cytosol to a membrane fraction. Fluorescence microscopy suggests that this fraction consists of post-Golgi AP-3 vesicles that have failed to dock or fuse at the vacuole membrane. We propose that AP-3 remains associated with budded vesicles, interacts with Vps41 and HOPS upon vesicle docking at the vacuole, and finally dissociates during docking or fusion.

scholarly journals RUSC2 and WDR47 oppositely regulate kinesin-1–dependent distribution of ATG9A to the cell periphery

2021 ◽  
pp. mbc.E21-06-0295
Author(s):  
Carlos M. Guardia ◽  
Akansha Jain ◽  
Rafael Mattera ◽  
Alex Friefeld ◽  
Yan Li ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Transmembrane Protein ◽  
Adaptor Protein ◽  
Negative Regulator ◽  
Cell Periphery ◽  
Repeat Domain ◽  
Peripheral Area ◽  
Microtubule Motor ◽  
Golgi Network ◽  
Perinuclear Area

Autophagy-related protein 9 (ATG9) is a transmembrane protein component of the autophagy machinery that cycles between the trans-Golgi network (TGN) in the perinuclear area and other compartments in the peripheral area of the cell. In mammalian cells, export of the ATG9A isoform from the TGN into ATG9A-containing vesicles is mediated by the adaptor protein 4 (AP-4) complex. However, the mechanisms responsible for the subsequent distribution of these vesicles to the cell periphery is unclear. Herein we show that the AP-4–accessory protein RUSC2 couples ATG9A-containing vesicles to the plus-end-directed microtubule motor kinesin-1 via an interaction between a disordered region of RUSC2 and the kinesin-1 light chain (KLC). This interaction is counteracted by the microtubule-associated WD40-repeat domain 47 protein (WDR47). These findings uncover a mechanism for the peripheral distribution of ATG9A-containing vesicles, involving the function of RUSC2 as a kinesin-1 adaptor and WDR47 as a negative regulator of this function.

scholarly journals Role of Vma21p in Assembly and Transport of the Yeast Vacuolar ATPase

2004 ◽  
Vol 15 (11) ◽  
pp. 5075-5091 ◽  
Author(s):  
Per Malkus ◽  
Laurie A. Graham ◽  
Tom H. Stevens ◽  
Randy Schekman
Keyword(s):  
Atp Hydrolysis ◽  
Proton Translocation ◽  
Wild Type ◽  
Vitro Assay ◽  
Accessory Factor ◽  
Transport Vesicles ◽  
Er Export

The Saccharomyces cerevisiae vacuolar H+-ATPase (V-ATPase) is a multisubunit complex composed of a peripheral membrane sector (V1) responsible for ATP hydrolysis and an integral membrane sector (V0) required for proton translocation. Biogenesis of V0 requires an endoplasmic reticulum (ER)-localized accessory factor, Vma21p. We found that in vma21Δ cells, the major proteolipid subunit of V0 failed to interact with the 100-kDa V0 subunit, Vph1p, indicating that Vma21p is necessary for V0 assembly. Immunoprecipitation of Vma21p from wild-type membranes resulted in coimmunoprecipitation of all five V0 subunits. Analysis of vmaΔ strains showed that binding of V0 subunits to Vma21p was mediated by the proteolipid subunit Vma11p. Although Vma21p/proteolipid interactions were independent of Vph1p, Vma21p/Vph1p association was dependent on all other V0 subunits, indicating that assembly of V0 occurs in a defined sequence, with Vph1p recruitment into a Vma21p/proteolipid/Vma6p complex representing the final step. An in vitro assay for ER export was used to demonstrate preferential packaging of the fully assembled Vma21p/proteolipid/Vma6p/Vph1p complex into COPII-coated transport vesicles. Pulse-chase experiments showed that the interaction between Vma21p and V0 was transient and that Vma21p/V0 dissociation was concomitant with V0/V1 assembly. Blocking ER export in vivo stabilized the interaction between Vma21p and V0 and abrogated assembly of V0/V1. Although a Vma21p mutant lacking an ER-retrieval signal remained associated with V0 in the vacuole, this interaction did not affect the assembly of vacuolar V0/V1 complexes. We conclude that Vma21p is not involved in regulating the interaction between V0 and V1 sectors, but that it has a crucial role in coordinating the assembly of V0 subunits and in escorting the assembled V0 complex into ER-derived transport vesicles.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

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