Tom1, a VHS Domain-containing Protein, Interacts with Tollip, Ubiquitin, and Clathrin

Yamakami, Megumi; Yoshimori, Tamotsu; Yokosawa, Hideyoshi

doi:10.1074/jbc.m306740200

Cited by 120 publications

(136 citation statements)

References 38 publications

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“…Similarities include interactions with Hrs and ubiquitin through their VHS and GAT domains, respectively, and interaction with TSG101. In addition, GGAs and Toms undergo mono-ubiquitination (20,21), they can localize at endosomes (18,49), and they are capable of binding to clathrin heavy chain through typical clathrin-binding motifs (21,28).…”

Section: Discussionmentioning

confidence: 99%

Interactions of TOM1L1 with the Multivesicular Body Sorting Machinery

Puertollano

2005

Journal of Biological Chemistry

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Tom1L1 (Tom1-like1) and related proteins Tom1 (Target of Myb1) and Tom1L2 (Tom1-like2) constitute a new protein family characterized by the presence of a VHS (Vps27p/Hrs/Stam) domain in the N-terminal portion followed by a GAT (GGA and Tom) domain. Recently it was demonstrated that the GAT domain of both Tom1 and Tom1L1 binds ubiquitin, suggesting that these proteins might participate in the sorting of ubiquitinated proteins into multivesicular bodies (MVBs). Here we report a novel interaction between Tom1L1 and members of the MVB sorting machinery. Specifically, we found that the VHS domain of Tom1L1 interacts with Hrs (Hepatocyte growth factor-regulated tyrosine kinase substrate), whereas a PTAP motif, located between the VHS and GAT domain of Tom1L1, is responsible for binding to TSG101 (tumor susceptibility gene 101). Myc epitopetagged Tom1L1 showed a cytosolic distribution but was recruited to endosomes following Hrs expression. In addition, Tom1L1 possesses several tyrosine motifs at the C-terminal region that mediate interactions with members of the Src family kinases and other signaling proteins such as Grb2 and p85. We showed that a fraction of Fyn kinase localizes at endosomes and that this distribution becomes more evident after epidermal growth factor internalization. Moreover, expression of a constitutive active form of Fyn also promoted the recruitment of Tom1L1 to enlarged endosomes. Taken together, we propose that Tom1L1 could act as an intermediary between signaling and degradative pathways.Regulated degradation of cell surface proteins, particularly receptors involved in signaling pathways, is essential for the control of many biological processes, including cell proliferation, survival, migration, and differentiation (1, 2). Internalized membrane-protein cargo can be delivered either to recycling vesicles for transport back to the cell surface or to late endosomes for transfer to lysosomes and degradation. Multivesicular bodies (MVBs) 1 are the compartments where this sorting event takes place (3). Thus, proteins to be degraded are included into small vesicles that invaginate into the lumen of the endosome. Subsequent fusion of MVBs with lysosomes releases these vesicles into the lysosome lumen, where they are degraded by lysosomal hydrolases. In contrast, proteins that remain in the limiting membrane of MVBs are recycled to the trans-Golgi network (TGN) or plasma membrane. In the last few years, a number of genetic and biochemical studies have allowed the characterization of the molecular machinery implicated in the formation of MVBs. Hrs appears to be the first protein to be recruited to endosomes (4 -6) through an interaction of its FIVE domain with phosphatidylinositol 3-phosphate (7), a lipid highly enriched in endosomal membranes (8). This is followed by the consecutive recruitment of three multisubunit complexes termed ESCRT-I (9), ESCRT-II (10), and ESCRT-III (11). Finally, the AAA-type ATPase Vps4 binds ESCRT-III and, following MVB vesicle formation, promotes the dissociation of the E...

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Section: Discussionmentioning

confidence: 99%

Interactions of TOM1L1 with the Multivesicular Body Sorting Machinery

Puertollano

2005

Journal of Biological Chemistry

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“…Peptide mass fingerprinting was performed as described previously [19] Tris-HCl, pH 7.5, 150 mM NaCl, 0.2% Nonidet P-40, 10% glycerol, and 1 mM phenylmethylsulfonyl fluoride, and the supernatant of the cell lysate was subjected to affinity purification using S-protein-immobilized agarose beads (Novagen). The resulting precipitate was washed three times with buffer B and subjected to Western blotting.…”

Section: Sds-page and Western Blotting Isolated Isgylated Proteins Wmentioning

confidence: 99%

Identification and Herc5-mediated ISGylation of novel target proteins

Takeuchi

Inoue

Yokosawa

2006

Biochemical and Biophysical Research Communications

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ISG15, a protein containing two ubiquitin-like domains, is an interferon-stimulated gene product that functions in antiviral response and is conjugated to various cellular proteins (ISGylation) upon interferon stimulation. ISGylation occurs via a pathway similar to the pathway for ubiquitination that requires the sequential action of E1/E2/E3: The E1 (UBE1L), E2 (UbcH8), and E3 (Efp/Herc5) enzymes for ISGylation have been hitherto identified. In this study, we identified six novel candidate target proteins for ISGylation by a proteomic approach. Four candidate target proteins were demonstrated to be ISGylated in UBE1L-and UbcH8-dependent manners, and ISGylation of the respective target proteins was stimulated by Herc5. In addition, Herc5 was capable of binding with the respective target proteins. Thus, these results suggest that Herc5 functions as a general E3 ligase for protein ISGylation.

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“…In silico analysis of a number of miRNA target prediction databases shows that TOM1 is a potential target of miR-126. TOM1 is a member of a family of proteins containing an N-terminal VHS (Vps27p/Hrs/STAM) domain reported to be involved in intracellular trafficking (14). Previous studies have shown that TOM1 forms a complex with Toll-interacting protein (Tollip), a negative regulator of TLR2, TLR4, and IL-1RI signaling.…”

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confidence: 99%