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Vol. 17, Issue 9, 3907-3920, September 2006

This Article Full Text Full Text (PDF) Supplemental Material All Versions of this Article: E06-05-0410v1 17/9/3907    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Costaguta, G. Articles by Payne, G. S. Search for Related Content PubMed PubMed Citation Articles by Costaguta, G. Articles by Payne, G. S.

Distinct Roles for TGN/Endosome Epsin-like Adaptors Ent3p and Ent5p

Giancarlo Costaguta^*, Mara C. Duncan^*, G. Esteban Fernández^*, Grace H. Huang, and Gregory S. Payne^*

*Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095; and Department of Biostatistics, School of Public Health, UCLA, Los Angeles, CA 90095

Submitted May 11, 2006; Revised June 12, 2006; Accepted June 14, 2006
Monitoring Editor: Janet Shaw

Clathrin adaptors are key factors in clathrin-coated vesicle formation, coupling clathrin to cargo and/or the lipid bilayer. A physically interacting network of three classes of adaptors participate in clathrin-mediated traffic between the trans-Golgi network (TGN) and endosomes: AP-1, Gga proteins, and epsin-like proteins. Here we investigate functional relationships within this network through transport assays and protein localization analysis in living yeast cells. We observed that epsin-like protein Ent3p preferentially localized with Gga2p, whereas Ent5p distributed equally between AP-1 and Gga2p. Ent3p was mislocalized in Gga-deficient but not in AP-1–deficient cells. In contrast, Ent5p retained localization in cells lacking either or both AP-1 and Gga proteins. The Ent proteins were dispensable for AP-1 or Gga localization. Synthetic genetic growth and -factor maturation defects were observed when ent5 but not ent3 was introduced together with deletions of the GGA genes. In AP-1–deficient cells, ent3 and to a lesser extent ent5 caused minor -factor maturation defects, but together resulted in a near-lethal phenotype. Deletions of ENT3 and ENT5 also displayed synthetic defects similar to, but less severe than, synthetic effects of AP-1 and Gga inactivation. These results differentiate Ent3p and Ent5p function in vivo, suggesting that Ent3p acts primarily with Gga proteins, whereas Ent5p acts with both AP-1 and Gga proteins but is more critical for AP-1–mediated transport. The data also support a model in which the Ent adaptors provide important accessory functions to AP-1 and Gga proteins in TGN/endosome traffic.

This article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E06-05-0410) on June 21, 2006.

Address correspondence to: Gregory S. Payne (gpayne{at}mednet.ucla.edu)

Abbreviations used: CCV, clathrin-coated vesicle; TGN, trans-Golgi network; CPS, carboxypeptidase S; ALP, alkaline phosphatase; ts, thermosensitive; ENTH, epsin N-terminal homology; ANTH, AP180 N-terminal homology; mRFP, monomeric red fluorescent protein; GFP, green fluorescent protein.

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