Exp Mol Med.  2001 Dec;33(4):245-250.

Cleavage of purified neuronal clathrin assembly protein (CALM) by caspase 3 and calpain

• Kim JA
• Kim HL

Abstract

The most efficient means of protein internalization from the membrane are through clathrin-coated pits, which concentrate protein interactions with the clathrin-associated assembly protein complex AP-2 and internalization signals in the cytoplasmic domain of transmembrane proteins. Binding of clathrin assembly protein to clathrin triskelia induces their assembly into clathrin-coated vesicles (CCVs). Due to a difficulty of isolating clathrin molecules from their complex or assembly state in the cells, most of the studies were carried out with recombinant clathrin proteins, which may present different conformation and structural variation. In this study, we have developed an efficient method of isolating the native clathrin assembly protein lymphoid myeloid (CALM) from the bovine brain that is enriched with clathrin and clathrin associated proteins and characterized by their sensitivity to proteases and it's ability to form CCV. The purified CALM has molecular weight of approximately 100,000 dalton on SDS-PAGE, which is consistent with the result of in vitro translation. The purified CALM protein could promote the assembly of clathrin triskelia into clathrin cage, and cleaved CALM proteolysed by caspase 3 and calpain could not promote them. In this respect, our data support a model in which CALM functions like AP180 as a monomeric clathrin assembly protein and might take part in apoptotic process in neuronal cells.

Keyword

clathrin-coated vesicle; CALM; caspase; expression

MeSH Terms

Adaptor Proteins
Animal
Brain Chemistry
Calpain/*metabolism
Carrier Proteins
Caspases/*metabolism
Cattle
Clathrin/*metabolism
Coated Pits, Cell-Membrane/*metabolism
Hydrolysis
Membrane Proteins
Molecular Weight
Nerve Tissue Proteins/chemistry/*isolation & purification/metabolism
Neurons/*chemistry
Protein Binding
Protein Conformation
Recombinant Proteins/chemistry/metabolism