In vitro binding of plasma membrane-coated vesicle adaptors to the cytoplasmic domain of lysosomal acid phosphatase.

Sorting of the newly synthesized membrane-bound precursor of lysosomal acid phosphatase (LAP) involves internalization from the plasma membrane via clathrin-coated pits. Using an in vitro system, we present direct evidence for high affinity interaction of the cytoplasmic domain of LAP with the amino-terminal trunk portion of plasma membrane-coated vesicle adaptors. Coated vesicle adaptors of the trans-Golgi network displayed poor binding to LAP, but high affinity binding to the cytoplasmic tail of the 46-kDa mannose 6-phosphate receptor, which is included in clathrin-coated pits of the trans-Golgi network. Binding of plasma membrane adaptors to the tail peptide of LAP required an internalization signal that contains either tyrosine or phenylalanine.