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Effect of Clathrin Assembly Lymphoid Myeloid Leukemia Protein Depletion on Clathrin Coat Formation
Author(s) -
Meyerholz Anika,
Hinrichsen Lars,
Groos Stephanie,
Esk PeterChristopher,
Brandes Gudrun,
Ungewickell Ernst J.
Publication year - 2005
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.1600-0854.2005.00355.x
Subject(s) - clathrin , biology , microbiology and biotechnology , endocytic cycle , clathrin adaptor proteins , endosome , signal transducing adaptor protein , vesicle , endocytosis , receptor , biochemistry , membrane , signal transduction , intracellular
The endocytic accessory clathrin assembly lymphoid myeloid leukemia protein (CALM) is the ubiquitously expressed homolog of the neuron‐specific protein AP180 that has been implicated in the retrieval of synaptic vesicle. Here, we show that CALM associates with the α‐appendage domain of the AP2 adaptor via the three peptide motifs 420 DPF, 375 DIF and 489 FESVF and to a lesser extent with the amino‐terminal domain of the clathrin heavy chain. Reducing clathrin levels by RNA interference did not significantly affect CALM localization, but depletion of AP2 weakens its association with the plasma membrane. In cells, where CALM levels were reduced by RNA interference, AP2 and clathrin remained organized in somewhat enlarged bright fluorescent puncta. Electron microscopy showed that the depletion of CALM drastically affected the clathrin lattice structure. Round‐coated buds, which are the predominant features in control cells, were replaced by irregularly shaped buds and long clathrin‐coated tubules. Moreover, we noted an increase in the number of very small cages that formed on flat lattices. Furthermore, we noticed a redistribution of endosomal markers and AP1 in cells that were CALM depleted. Taken together, our findings indicate a critical role for CALM in the regulation and orderly progression of coated bud formation at the plasma membrane.