scholarly journals SVIP Is a Novel VCP/p97-interacting Protein Whose Expression Causes Cell Vacuolation

2003 ◽  
Vol 14 (1) ◽  
pp. 262-273 ◽  
Author(s):  
Masami Nagahama ◽  
Mie Suzuki ◽  
Yuko Hamada ◽  
Kiyotaka Hatsuzawa ◽  
Katsuko Tani ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coiled Coil ◽  
Adaptor Proteins ◽  
Interacting Protein ◽  
Cellular Processes ◽  
Coiled Coil Region ◽  
Acid Protein ◽  
Extensive Cell ◽  
Dependent Protein ◽  
Amino Acid Protein

VCP/p97 is involved in a variety of cellular processes, including membrane fusion and ubiquitin-dependent protein degradation. It has been suggested that adaptor proteins such as p47 and Ufd1p confer functional versatility to VCP/p97. To identify novel adaptors, we searched for proteins that interact specifically with VCP/p97 by using the yeast two-hybrid system, and discovered a novel VCP/p97-interacting protein named smallVCP/p97-interactingprotein (SVIP). Rat SVIP is a 76-amino acid protein that contains two putative coiled-coil regions, and potential myristoylation and palmitoylation sites at the N terminus. Binding experiments revealed that the N-terminal coiled-coil region of SVIP, and the N-terminal and subsequent ATP-binding regions (ND1 domain) of VCP/p97, interact with each other. SVIP and previously identified adaptors p47 and ufd1p interact with VCP/p97 in a mutually exclusive manner. Overexpression of full-length SVIP or a truncated mutant did not markedly affect the structure of the Golgi apparatus, but caused extensive cell vacuolation reminiscent of that seen upon the expression of VCP/p97 mutants or polyglutamine proteins in neuronal cells. The vacuoles seemed to be derived from endoplasmic reticulum membranes. These results together suggest that SVIP is a novelVCP/p97 adaptor whose function is related to the integrity of the endoplasmic reticulum.

scholarly journals The E3 Ligase CHIP: Insights into Its Structure and Regulation

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Indranil Paul ◽  
Mrinal K. Ghosh
Keyword(s):  
Quality Control ◽  
Tandem Repeats ◽  
Current Knowledge ◽  
Coiled Coil ◽  
E3 Ligase ◽  
Review Article ◽  
Regulatory Mechanisms ◽  
Carboxy Terminus ◽  
Interacting Protein ◽  
Coiled Coil Region

The carboxy-terminus of Hsc70 interacting protein (CHIP) is a cochaperone E3 ligase containing three tandem repeats of tetratricopeptide (TPR) motifs and a C-terminal U-box domain separated by a charged coiled-coil region. CHIP is known to function as a central quality control E3 ligase and regulates several proteins involved in a myriad of physiological and pathological processes. Recent studies have highlighted varied regulatory mechanisms operating on the activity of CHIP which is crucial for cellular homeostasis. In this review article, we give a concise account of our current knowledge on the biochemistry and regulation of CHIP.

Functional interactions between ubiquitin E2 enzymes and TRIM proteins

2011 ◽  
Vol 434 (2) ◽  
pp. 309-319 ◽  
Author(s):  
Luisa M. Napolitano ◽  
Ellis G. Jaffray ◽  
Ronald T. Hay ◽  
Germana Meroni
Keyword(s):  
Coiled Coil ◽  
Specific Interactions ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Coiled Coil Region ◽  
Physiological Relevance ◽  
Tripartite Motif ◽  
E2 Enzymes ◽  
Specific Reactions ◽  
Trim Proteins

The TRIM (tripartite motif) family of proteins is characterized by the presence of the tripartite motif module, composed of a RING domain, one or two B-box domains and a coiled-coil region. TRIM proteins are involved in many cellular processes and represent the largest subfamily of RING-containing putative ubiquitin E3 ligases. Whereas their role as E3 ubiquitin ligases has been presumed, and in several cases established, little is known about their specific interactions with the ubiquitin-conjugating E2 enzymes or UBE2s. In the present paper, we report a thorough screening of interactions between the TRIM and UBE2 families. We found a general preference of the TRIM proteins for the D and E classes of UBE2 enzymes, but we also revealed very specific interactions between TRIM9 and UBE2G2, and TRIM32 and UBE2V1/2. Furthermore, we demonstrated that the TRIM E3 activity is only manifest with the UBE2 with which they interact. For most specific interactions, we could also observe subcellular co-localization of the TRIM involved and its cognate UBE2 enzyme, suggesting that the specific selection of TRIM–UBE2 pairs has physiological relevance. Our findings represent the basis for future studies on the specific reactions catalysed by the TRIM E3 ligases to determine the fate of their targets.

scholarly journals Structural insights into WHAMM-mediated cytoskeletal coordination during membrane remodeling

2012 ◽  
Vol 199 (1) ◽  
pp. 111-124 ◽  
Author(s):  
Qing-Tao Shen ◽  
Peter P. Hsiue ◽  
Charles V. Sindelar ◽  
Matthew D. Welch ◽  
Kenneth G. Campellone ◽  
...  
Keyword(s):  
Intracellular Transport ◽  
Coiled Coil ◽  
Tubular Structures ◽  
Terminal Portion ◽  
Actin Nucleation ◽  
Cellular Processes ◽  
Coiled Coil Region ◽  
Membrane Tubulation ◽  
Underlying Mechanisms ◽  
Structural Insights

The microtubule (MT) and actin cytoskeletons drive many essential cellular processes, yet fairly little is known about how their functions are coordinated. One factor that mediates important cross talk between these two systems is WHAMM, a Golgi-associated protein that utilizes MT binding and actin nucleation activities to promote membrane tubulation during intracellular transport. Using cryoelectron microscopy and other biophysical and biochemical approaches, we unveil the underlying mechanisms for how these activities are coordinated. We find that WHAMM bound to the outer surface of MT protofilaments via a novel interaction between its central coiled-coil region and tubulin heterodimers. Upon the assembly of WHAMM onto MTs, its N-terminal membrane-binding domain was exposed at the MT periphery, where it can recruit vesicles and remodel them into tubular structures. In contrast, MT binding masked the C-terminal portion of WHAMM and prevented it from promoting actin nucleation. These results give rise to a model whereby distinct MT-bound and actin-nucleating populations of WHAMM collaborate during membrane tubulation.

scholarly journals MICAL-L1 Links EHD1 to Tubular Recycling Endosomes and Regulates Receptor Recycling

2009 ◽  
Vol 20 (24) ◽  
pp. 5181-5194 ◽  
Author(s):  
Mahak Sharma ◽  
Sai Srinivas Panapakkam Giridharan ◽  
Juliati Rahajeng ◽  
Naava Naslavsky ◽  
Steve Caplan
Keyword(s):  
Coiled Coil ◽  
Live Cells ◽  
Endocytic Recycling ◽  
Interacting Protein ◽  
Recycling Endosomes ◽  
Coiled Coil Region ◽  
Membrane Tubules ◽  
Tubular Membranes

Endocytic recycling of receptors and lipids occurs via a complex network of tubular and vesicular membranes. EHD1 is a key regulator of endocytosis and associates with tubular membranes to facilitate recycling. Although EHD proteins tubulate membranes in vitro, EHD1 primarily associates with preexisting tubules in vivo. How EHD1 is recruited to these tubular endosomes remains unclear. We have determined that the Rab8-interacting protein, MICAL-L1, associates with EHD1, with both proteins colocalizing to long tubular membranes, in vitro and in live cells. MICAL-L1 is a largely uncharacterized member of the MICAL-family of proteins that uniquely contains two asparagine-proline-phenylalanine motifs, sequences that typically interact with EH-domains. Our data show that the MICAL-L1 C-terminal coiled-coil region is necessary and sufficient for its localization to tubular membranes. Moreover, we provide unexpected evidence that endogenous MICAL-L1 can link both EHD1 and Rab8a to these structures, as its depletion leads to loss of the EHD1-Rab8a interaction and the absence of both of these proteins from the membrane tubules. Finally, we demonstrate that MICAL-L1 is essential for efficient endocytic recycling. These data implicate MICAL-L1 as an unusual type of Rab effector that regulates endocytic recycling by recruiting and linking EHD1 and Rab8a on membrane tubules.

scholarly journals Accommodation of structural rearrangements in the huntingtin-interacting protein 1 coiled-coil domain

2010 ◽  
Vol 66 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Jeremy D. Wilbur ◽  
Peter K. Hwang ◽  
Frances M. Brodsky ◽  
Robert J. Fletterick
Keyword(s):  
Light Chain ◽  
Coiled Coil ◽  
Actin Binding ◽  
Interacting Protein ◽  
Similar Region ◽  
Coiled Coil Domain ◽  
Coiled Coil Region ◽  
Huntingtin Interacting Protein 1 ◽  
Conformational Regulation ◽  
Huntingtin Interacting Protein

Huntingtin-interacting protein 1 (HIP1) is an important link between the actin cytoskeleton and clathrin-mediated endocytosis machinery. HIP1 has also been implicated in the pathogenesis of Huntington's disease. The binding of HIP1 to actin is regulated through an interaction with clathrin light chain. Clathrin light chain binds to a flexible coiled-coil domain in HIP1 and induces a compact state that is refractory to actin binding. To understand the mechanism of this conformational regulation, a high-resolution crystal structure of a stable fragment from the HIP1 coiled-coil domain was determined. The flexibility of the HIP1 coiled-coil region was evident from its variation from a previously determined structure of a similar region. A hydrogen-bond network and changes in coiled-coil monomer interaction suggest that the HIP1 coiled-coil domain is uniquely suited to allow conformational flexibility.

scholarly journals PSTPIP: A Tyrosine Phosphorylated Cleavage Furrow–associated Protein that Is a Substrate for a PEST Tyrosine Phosphatase

1997 ◽  
Vol 138 (4) ◽  
pp. 845-860 ◽  
Author(s):  
Susan Spencer ◽  
Donald Dowbenko ◽  
Jill Cheng ◽  
Wenlu Li ◽  
Jennifer Brush ◽  
...  
Keyword(s):  
Tyrosine Phosphatase ◽  
Coiled Coil ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Cleavage Furrow ◽  
Cortical Actin ◽  
Interacting Protein ◽  
Hematopoietic Stem ◽  
Coiled Coil Region ◽  
Negative Effect

We have investigated proteins which interact with the PEST-type protein tyrosine phosphatase, PTP hematopoietic stem cell fraction (HSCF), using the yeast two-hybrid system. This resulted in the identification of proline, serine, threonine phosphatase interacting protein (PSTPIP), a novel member of the actin- associated protein family that is homologous to Schizosaccharomyces pombe CDC15p, a phosphorylated protein involved with the assembly of the actin ring in the cytokinetic cleavage furrow. The binding of PTP HSCF to PSTPIP was induced by a novel interaction between the putative coiled-coil region of PSTPIP and the COOH-terminal, proline-rich region of the phosphatase. PSTPIP is tyrosine phosphorylated both endogenously and in v-Src transfected COS cells, and cotransfection of dominant-negative PTP HSCF results in hyperphosphorylation of PSTPIP. This dominant-negative effect is dependent upon the inclusion of the COOH-terminal, proline-rich PSTPIP-binding region of the phosphatase. Confocal microscopy analysis of endogenous PSTPIP revealed colocalization with the cortical actin cytoskeleton, lamellipodia, and actin-rich cytokinetic cleavage furrow. Overexpression of PSTPIP in 3T3 cells resulted in the formation of extended filopodia, consistent with a role for this protein in actin reorganization. Finally, overexpression of mammalian PSTPIP in exponentially growing S. pombe results in a dominant-negative inhibition of cytokinesis. PSTPIP is therefore a novel actin-associated protein, potentially involved with cytokinesis, whose tyrosine phosphorylation is regulated by PTP HSCF.

scholarly journals Division of Mitochondria Requires a NovelDNM1-interacting Protein, Net2p

2001 ◽  
Vol 12 (2) ◽  
pp. 309-321 ◽  
Author(s):  
Kara L. Cerveny ◽  
J. Michael McCaffery ◽  
Robert E. Jensen
Keyword(s):  
Molecular Mechanisms ◽  
Mitochondrial Fission ◽  
Coiled Coil ◽  
Protein Fluorescence ◽  
Uncharacterized Protein ◽  
Interacting Protein ◽  
Genome Wide ◽  
Coiled Coil Region ◽  
A Genome ◽  
New Gene

Mitochondria are dynamic organelles that undergo frequent division and fusion, but the molecular mechanisms of these two events are not well understood. Dnm1p, a mitochondria-associated, dynamin-related GTPase was previously shown to mediate mitochondrial fission. Recently, a genome-wide yeast two-hybrid screen identified an uncharacterized protein that interacts with Dnm1p. Cells disrupted in this new gene, which we call NET2, contain a single mitochondrion that consists of a network formed by interconnected tubules, similar to the phenotype of dnm1Δ cells. NET2 encodes a mitochondria-associated protein with a predicted coiled-coil region and six WD-40 repeats. Immunofluorescence microscopy indicates that Net2p is located in distinct, dot-like structures along the mitochondrial surface, many of which colocalize with the Dnm1 protein. Fluorescence and immunoelectron microscopy shows that Dnm1p and Net2p preferentially colocalize at constriction sites along mitochondrial tubules. Our results suggest that Net2p is a new component of the mitochondrial division machinery.

scholarly journals Huntingtin interacting protein 1 modulates the transcriptional activity of nuclear hormone receptors

2005 ◽  
Vol 170 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Ian G. Mills ◽  
Luke Gaughan ◽  
Craig Robson ◽  
Theodora Ross ◽  
Stuart McCracken ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Hormone Receptors ◽  
Nuclear Translocation ◽  
Coiled Coil ◽  
Adaptor Proteins ◽  
Cellular Transformation ◽  
Interacting Protein ◽  
Response Elements ◽  
Huntingtin Interacting Protein 1 ◽  
Huntingtin Interacting Protein

Internalization of activated receptors regulates signaling, and endocytic adaptor proteins are well-characterized in clathrin-mediated uptake. One of these adaptor proteins, huntingtin interacting protein 1 (HIP1), induces cellular transformation and is overexpressed in some prostate cancers. We have discovered that HIP1 associates with the androgen receptor through a central coiled coil domain and is recruited to DNA response elements upon androgen stimulation. HIP1 is a novel androgen receptor regulator, significantly repressing transcription when knocked down using a silencing RNA approach and activating transcription when overexpressed. We have also identified a functional nuclear localization signal at the COOH terminus of HIP1, which contributes to the nuclear translocation of the protein. In conclusion, we have discovered that HIP1 is a nucleocytoplasmic protein capable of associating with membranes and DNA response elements and regulating transcription.

Kermit, a frizzled interacting protein, regulates frizzled 3 signaling in neural crest development

Development ◽  
2001 ◽  
Vol 128 (19) ◽  
pp. 3665-3674 ◽  
Author(s):  
Change Tan ◽  
Matthew A. Deardorff ◽  
Jean-Pierre Saint-Jeannet ◽  
Jing Yang ◽  
Arpine Arzoumanian ◽  
...  
Keyword(s):  
Neural Crest ◽  
Antisense Oligonucleotides ◽  
Pdz Domain ◽  
Interacting Protein ◽  
Reading Frame ◽  
Neural Crest Development ◽  
C Terminus ◽  
Acid Protein ◽  
New Protein ◽  
Amino Acid Protein

Wnts are a family of secreted glycoproteins that are important for multiple steps in early development. Accumulating evidence suggests that frizzled genes encode receptors for Wnts. However, the mechanism through which frizzleds transduce a signal and the immediate downstream components that convey that signal are unclear. We have identified a new protein, Kermit, that interacts specifically with the C-terminus of Xenopus frizzled-3 (Xfz3). Kermit is a 331 amino acid protein with a central PDZ domain. Kermit mRNA is expressed throughout Xenopus development and is localized to neural tissue in a pattern that overlaps Xfz3 expression temporally and spatially. Co-expression of Xfz3 and Kermit results in a dramatic translocation of Kermit to the plasma membrane. Inhibition of Kermit function with morpholino antisense oligonucleotides directed against the 5′ untranslated region of Kermit mRNA blocks neural crest induction by Xfz3, and this is rescued by co-injection of mRNA encoding the Kermit open reading frame. These observations suggest that Kermit is required for Wnt/frizzled signaling in neural crest development. To the best of our knowledge, Kermit is the first protein identified that interacts directly with the cytoplasmic portion of frizzleds to modulate their signaling activity.

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