Clathrin-mediated endocytosis (CME) is a cellular trafficking process in which 
cargoes and lipids are internalized from the plasma membrane into vesicles 
coated with clathrin and adaptor proteins. CME is essential for many 
developmental and physiological processes in plants, but its underlying 
mechanism is not well characterized compared with that in yeast and animal 
systems. Here, we searched for new factors involved in CME in Arabidopsis 
thaliana by performing tandem affinity purification of proteins that interact 
with clathrin light chain, a principal component of the clathrin coat. Among the 
confirmed interactors, we found two putative homologs of the clathrin-coat 
uncoating factor auxilin previously described in non-plant systems. 
Overexpression of AUXILIN-LIKE1 and AUXILIN-LIKE2 in Arabidopsis caused an 
arrest of seedling growth and development. This was concomitant with inhibited 
endocytosis due to blocking of clathrin recruitment after the initial step of 
adaptor protein binding to the plasma membrane. By contrast, auxilin-like1/2 
loss-of-function lines did not present endocytosis-related developmental or 
cellular phenotypes under normal growth conditions. This work contributes to the 
ongoing characterization of the endocytotic machinery in plants and provides a 
robust tool for conditionally and specifically interfering with CME in 
Arabidopsis.