Human basic fibroblast growth factor gene encodes four polypeptides: three initiate translation from non-AUG codons

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Human basic fibroblast growth factor (bFGF) is an angiogenic polypeptide mitogen.
• bFGF is found in various mesoderm- and neuroectoderm-derived tissues.
• Predicted bFGF gene product is 17.8-kDa (155 amino acids) initiated at an ATG codon.

Purpose of the Study:

• To investigate the molecular forms of bFGF expressed in the human cell line SK-HEP-1.
• To identify the initiation sites of different bFGF molecular weight forms.
• To characterize the relationship between the various bFGF proteins.

Main Methods:

• Analysis of molecular forms of bFGF in SK-HEP-1 cell line.
• Identification of translational initiation sites (AUG and non-AUG codons).
• Characterization of N-terminal sequences of bFGF variants.

Main Results:

• SK-HEP-1 cells coexpress four molecular forms of bFGF (17.8, 22.5, 23.1, and 24.2 kDa).
• The 17.8-kDa bFGF initiates at the predicted AUG codon.
• Higher molecular weight bFGF forms initiate at non-AUG codons, representing N-terminal extensions.

Conclusions:

• Human bFGF expression involves initiation at non-AUG codons, generating multiple protein isoforms.
• These findings expand the understanding of bFGF translational regulation.
• Multiple bFGF forms may have distinct biological functions due to N-terminal variations.