METAP2 - Structure

Structure

In living organisms, the start codon that initiates protein synthesis codes for either methionine (eukaryotes) or formylmethionine (prokaryotes). In E. coli (prokaryote), an enzyme called formylmethionine deformylase can cleave the formyl group, leaving just the N-terminal methionine residue. For proteins with small, uncharged penultimate N-terminal residues, a methionine aminopeptidase can cleave the methionine residue. The number of genes encoding for a methionine aminopeptidase varies between organisms. In E. coli, there is only one known MetAP, a 29,333 Da monomeric enzyme coded for by a gene consisting of 264 codons. The knockout of this gene in E. coli leads to cell inviability. In humans, there are two genes encoding MetAP, MetAP1 and MetAP2. MetAP1 codes for a 42 kDa enzyme, while MetAP2 codes for a 67 kDa enzyme. Yeast MetAP1 is 40 percent homologous to E. coli MetAP; within S. cerevisiae, MetAP2 is 22 percent homologous with the sequence of MetAP1; MetAP2 is highly conserved between S. cerevisiae and humans. In contrast to prokaryotes, eukaryotic S. cerevisiae strains lacking the gene for either MetAP1 or MetAP2 are viable, but exhibit a slower growth rate than a control strain expressing both genes.