J. Hata et al., A CDNA-ENCODING FISH FIBROBLAST GROWTH FACTOR-II, WHICH LACKS ALTERNATIVE TRANSLATION INITIATION, The Journal of biological chemistry, 272(11), 1997, pp. 7285-7289
Here, we describe the isolation of a rainbow trout cDNA clone that con
tains the entire fibroblast growth factor-2 (FGF-2; basic FGF) coding
region. Interestingly, the rainbow trout cDNA contains a translation s
top codon just upstream of the primary initiating methionine codon and
so cannot give rise to the longer forms of FGF-2 that are produced in
mammals by alternative translation initiation at leucines farther ups
tream, Transfection of human FGF-2 cDNA into fish cells shows that fis
h cells can initiate protein synthesis at an upstream leucine CUG codo
n; surprisingly, however, synthesis is initiated only at the most 5' C
UG and not at the two subsequent CUG codons or the methionine AUG codo
n also used in mammalian cells. Like other FGF-2 proteins, bacterially
produced rainbow trout FGF-2 protein binds tightly to heparin-Sepharo
se and also promotes the proliferation of fibroblast cells. However, t
he protein differs from all others previously identified at amino acid
s 121-123, which are part of the proposed highly conserved receptor-bi
nding domain. Comparisons of the efficacies of recombinant wild-type a
nd mutant rainbow trout FGF-2 proteins demonstrate that these three am
ino acids are critical to the activity of FGF-2.