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 cedi ng region of the basic fibroblast growth factor (BFGF) gene of a marsu pial, the opossum Monodelphis domestica. The encoded protein is 156 am ino acids long. The BFGF gene of M. domestica is 82-87% identical to t he BFGF genes of placental mammals at the nucleotide level and 92-93% identical to these genes at the level of the amino acids encoded. Regi ons of the BFGF molecule important in heparin binding, high-affinity r eceptor binding, and biologic function are highly conserved between pl acental mammals and this marsupial. There are several AUG and CUG codo ns in the 5' region of the marsupial cDNA that may serve as alternate sites of translation initiation; use of these sites would produce amin o-terminally extended BFGF proteins. Amino-terminal extensions of BFGF in other species serve as nuclear localization signals. Conservered A +T-rich motifs in the 3' untranslated region of the marsupial mRNA pro bably serve to regulate mRNA stability. The high degree of evolutionar y conservation of BFGF in mammals suggests that the molecule plays an important role in normal growth and development and that stringent con trol of its activity is essential.