Serum albumin precursor
Homo sapiens (human)
Various molecules need to be transported through the blood between different parts of the body. The water soluble molecules, like sugar, are transported through the blood without help from other molecules. However, water insoluble molecules need to be carried by specific carriers that allow them to travel through the blood. Such molecules include fatty acids, steroids, amino acids, metals and various drugs. Serum albumin is the most abundant protein in blood plasma and is also found in tissues and bodily secretions. It is a carrier protein that can bind several different kinds of water insoluble molecules and transport them throughout the body via the blood. Some of the most important molecules transported by serum albumin are fatty acids. Fatty acids that are released by fat cells need to be transported to other cells throughout the body where they can be metabolized to release ATP which is required for numerous reactions in the body. Fatty acids bind to serum albumin in the deep crevices where their hydrophobic carbon tails are shielded from the surrounding water. Serum albumin also binds other water insoluble molecules, especially drugs like ibuprofen, aspirin and diazepam, among others, to deliver them throughout the body. Bovine serum albumin is often used in the laboratory to stabilize enzymes during experiments.
The structure shown is that of human serum albumin. This heart-shaped molecule consists of 3 similar domains of alpha-helices, known as domains I, II and III. Each domain is, in turn, made up of two helical subdomains with common structural motifs, known as A and B. The principal ligand binding site is in the hydrophobic cavities in the subdomains IIA and IIIA.
Protein Data Bank (PDB)
He, X.M. Carter, D.C.; "Atomic structure and chemistry of human serum albumin."; Nature; (1992) 358:209-215 PubMed:1630489.
author: Ashwini Patil