The word clathrin originates from the Latin word clāthrāre, meaning “to provide with a lattice”. Clathrin is a protein involved in receptor-mediated endocytosis.1 It was not discovered until 1975 by Barbara Pearse, a British biological scientist. Clathrin is a protein resembling a triskelion shape and is composed of three heavy chains and three light chains which come together to form a polyhedral lattice similar to a cage. The three heavy chains resemble three legs protruding from a center point. Some of the major functions of clathrin include lysosomal targeting, receptor-mediated endocytosis, and organelle biogenesis from the trans-Golgi network.3 The polyhedral lattice shape of clathrin largely determines its functionality, in that there are many binding sites for proteins on the heavy chains of the lattice as well.4
Structure
Individual Clathrin Molecule
An individual clathrin molecule is composed of three heavy chains, each being attached to a light chain. This structure is often referred to as a triskelion shape.1 The heavy chains of clathrin are made of an amino-terminal, a beta-propellor domain containing multiple repeats of the WD40 binding motif, alpha-helical zig-zags close to 30 amino acids in length, a lengthened alpha-helix where the threefold contacts, and a carboxy-terminal.1 The aforementioned zig-zags are what create the “leg” looking structure of the triskelion. 1
Part of the heavy chain is designated to bind to the light chains, of which there are two variations in mammals. The heavy chain and light chain bind through one long alpha helix towards the center of the protein. 1
Clathrin Lattice
Individual clathrin molecules can assemble into cage-like structures. When individual clathrin molecules come together, a lattice is formed where each lattice point is associated with the center of a triskelion (from the Greek word meaning “a three legged structure”)1
Disease
Relevance
Structural highlights
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