Interactions between Adaptor Protein-1 of the Clathrin Coat and Microtubules via Type 1a Microtubule-associated Proteins

Ena Orzech, Leonid Livshits, Julieta Leyt, Hana Okhrimenko, Vanda Reich, Shulamit Cohen, Aryeh Weiss, Naomi Melamed-Book, Mario Lebendiker, Yoram Altschuler, Benjamin Aroeti*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The classical view suggests that adaptor proteins of the clathrin coat mediate the sorting of cargo protein passengers into clathrin-coated pits and the recruitment of clathrin into budding areas in the donor membrane. In the present study, we provide biochemical and morphological evidence that the adaptor protein 1 (AP-1) adaptor of the trans-Golgi network clathrin interacts with microtubules. AP-1 in cytosolic extracts interacted with in vitro assembled microtubules, and these interactions were inhibited by ATP depletion of the extracts or in the presence of 5′-adenylylimidodiphosphate. An overexpressed γ-subunit of the AP-1 complex associated with microtubules, suggesting that this subunit may mediate the interaction of AP-1 with the cytoskeleton. Purified AP-1 did not interact with purified microtubules, but interaction occurred when an isolated microtubule-associated protein fraction was added to the reaction mix. The γ-adaptin subunit of AP-1 specifically co-immunoprecipitated with a microtubule-associated protein of type 1a from rat brain cytosol. This suggests that type 1a microtubule-associated protein may mediate the association of AP-1 with microtubules in the cytoplasm. The microtubule binding activity of AP-1 was markedly inhibited in cytosol of mitotic cells. By means of its interaction with microtubule-associated proteins, we propose novel roles for AP-1 adaptors in modulating the dynamics of the cytoskeleton, the stability and shape of coated organelles, and the loading of nascent AP-1-coated vesicles onto appropriate microtubular tracks.

Original languageAmerican English
Pages (from-to)31340-31348
Number of pages9
JournalJournal of Biological Chemistry
Volume276
Issue number33
DOIs
StatePublished - 17 Aug 2001

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