Characterization of cDNA encoding basic fibroblast growth factor of the marsupial Monodelphis domestica.

We have isolated and characterized a 1,593-bp cDNA containing the coding region of the basic fibroblast growth factor (BFGF) gene of a marsupial, the opossum Monodelphis domestica. The encoded protein is 156 amino acids long. The BFGF gene of M. domestica is 82-87% identical to the BFGF genes of placental mammals at the nucleotide level and 92-93% identical to these genes at the level of the amino acids encoded. Regions of the BFGF molecule important in heparin binding, high-affinity receptor binding, and biologic function are highly conserved between placental mammals and this marsupial. There are several AUG and CUG codons in the 5' region of the marsupial cDNA that may serve as alternate sites of translation initiation; use of these sites would produce amino-terminally extended BFGF proteins. Amino-terminal extensions of BFGF in other species serve as nuclear localization signals. Conserved A+T-rich motifs in the 3' untranslated region of the marsupial mRNA probably serve to regulate mRNA stability. The high degree of evolutionary conservation of BFGF in mammals suggests that the molecule plays an important role in normal growth and development and that stringent control of its activity is essential.