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A Single β Adaptin Contributes to AP 1 and AP 2 Complexes and Clathrin Function in D ictyostelium
Author(s) -
Thomas Sosa R.,
Weber Michelle M.,
Wen Yujia,
O'Halloran Theresa J.
Publication year - 2012
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.1600-0854.2011.01310.x
Subject(s) - biology , clathrin , microbiology and biotechnology , function (biology) , signal transducing adaptor protein , endocytosis , receptor , phosphorylation , genetics
The assembly of clathrin‐coated vesicles is important for numerous cellular processes, including nutrient uptake and membrane organization. Important contributors to clathrin assembly are four tetrameric assembly proteins, also called adaptor proteins ( APs ), each of which contains a β subunit. We identified a single β subunit, named β1/2, that contributes to both the AP 1 and AP 2 complexes of D ictyostelium . Disruption of the gene encoding β1/2 resulted in severe defects in growth, cytokinesis and development. Additionally, cells lacking β1/2 displayed profound osmoregulatory defects including the absence of contractile vacuoles and mislocalization of contractile vacuole markers. The phenotypes of β1/2 null cells were most similar to previously described phenotypes of clathrin and AP 1 mutants, supporting a particularly important contribution of AP 1 to clathrin pathways in D ictyostelium cells. The absence of β1/2 in cells led to significant reductions in the protein amounts of the medium‐sized subunits of the AP 1 and AP 2 complexes, establishing a role for the β subunit in the stability of the medium subunits. D ictyostelium β1/2 could resemble a common ancestor of the more specialized β1 and β2 subunits of the vertebrate AP complexes. Our results support the essential contribution of a single β subunit to the stability and function of AP 1 and AP 2 in a simple eukaryote.