Epidermal growth factor amino-acid sequence

Figure 47-10. Schematic diagram of the structure of human L-selectin. The extracellular portion contains an amino terminal domain homologous to C-type lectins and an adjacent epidermal growth factor-like domain. These are followed by a variable number of complement regulatory-like modules (numbered circles) and a transmembrane sequence (blackdiamond). A short cytoplasmic sequence (open rectangle) is at the carboxyl terminal. The structures of P- and E-selectin are similar to that shown except that they contain more complement-regulatory modules.The numbers of amino acids in L-, P-, and E- selectins, as deduced from the cDNA sequences, are 385,789, and 589, respectively. (Reproduced, with permission, from Bevilacqua MP, Nelson RM Selectins. J Clin Invest 1993 91 370.)...

All of the growth factors characterized so far are proteins (table 24.7). Many of them are cleaved from larger precursors. The 53-amino-acid epidermal growth factor (EGF) is cleaved from a precursor of 1,168 amino acids. This precursor is a membrane-spanning protein, with the EGF moiety and nine related sequences in the extracellular domain. EGF is homologous to several other growth factors,... 

Amino acid sequence analyses reveal the existence of more than 50 different growth factor receptors. These can be grouped into at least 18 families, notable examples of which include the (1) platelet-derived growth factor receptor family, (2) fibroblast growth factor receptor family, (3) epidermal growth factor receptor family, and (4) insulin-like growth factor receptor family. 

If a single gene is cloned in sufficient quantity, it can be sequenced (see Deoxyribonucleic acid) and the amino acid sequence of the gene product can be predicted from the nucleotide sequence of the DNA. For example, the amino acid sequences of the insulin receptor, nicotinic and muscarinic cholinergic acetylcholine receptors, epidermal growth factor precursor and many (thousands) other proteins have been predicted in this way. 

Figure 5-1. Comparison of the amino acid sequences of human urogastrone and mouse epidermal growth factor (EGF), with noncorresponding residues enclosed. (From Gregory H. Isolation and structure of urogastrone and Its relation to epidermal growth factor. Nature 257 325-327, 1975. Reproduced by permission from Nature, Vol 257, pp 325-327. Copyright 1975 Macmillan Magazines Ltd.)...

---