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AAK1 Regulates Numb Function at an Early Step in Clathrin‐Mediated Endocytosis
Author(s) -
Sorensen Erika B.,
Conner Sean D.
Publication year - 2008
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2008.00790.x
Subject(s) - numb , endocytic cycle , endocytosis , microbiology and biotechnology , biology , endosome , phosphorylation , internalization , clathrin , signal transducing adaptor protein , biochemistry , cell , intracellular
Numb is an endocytic protein that is proposed to influence clathrin‐coated pit assembly, although its mode of action and the mechanisms that regulate its activity are unknown. In this study, we show that Numb binds to and is phosphorylated by adaptor‐associated kinase 1 (AAK1), a key endocytic kinase. We find that AAK1 redistributes Numb to perinuclear endosomes when overexpressed, while kinase depletion causes Numb to accumulate at the plasma membrane. Overexpression of a Numb point mutant (T102A) that lacks the AAK1 phosphorylation site potently disrupts transferrin and low‐density lipoprotein internalization but does not impact EGF uptake. Consistent with Numb redistribution results, we find that T102A Numb no longer localizes to perinuclear endosomes. Instead, it is enriched at the plasma membrane where it shows elevated levels of colocalization with coated pit markers. Collectively, these observations demonstrate that Numb endocytic activity is regulated by AAK1 and that phosphorylation may be a critical step in promoting coated pit maturation.