NPFXD peptides specifically interact with the SHD1 domain. NPFXD is a clathrin-facilitated endocytic targeting signal. NPFXD was originally discovered in the cytoplasmic domain of the furin-like protease Kex2p [1]. Sla1 is thought to function as an endocytic adaptor [1].

1: Pan1p, End3p, and S1a1p, three yeast proteins required for normal cortical actin cytoskeleton organization, associate with each other and play essential roles in cell wall morphogenesis. Tang HY, Xu J, Cai M; Mol Cell Biol 2000;20:12-25. PMID:10594004