Structural requirements of FGF-1 for receptor binding and translocation into cells.


FGF-1 binds to and activates specific transmembrane receptors (FGFRs) and is subsequently internalized and translocated to the interior of the cell. To elucidate the role of the receptor in the translocation process, we studied the effects of the elimination of distinct sites of the ligand-receptor interaction. On the basis of the structure of the FGF-1-FGFR1 complex, we substituted four key amino acid residues of FGF-1 from the FGF-receptor binding site with alanines, constructing four point mutants and one double mutant. We determined by in vivo assays in NIH 3T3 cells the ability of the mutants to bind to specific FGF receptors, to stimulate DNA synthesis, and to activate downstream signaling pathways. We found that correct binding to the receptor is necessary for optimal stimulation of DNA synthesis. All four single mutants became phosphorylated to different extents, indicating that they were translocated to the cytosol/nucleus with varying efficiency. This indicates that despite a low affinity for FGFR, translocation to the cytosol/nucleus can still occur. However, simultaneous substitution in two of the positions led to a total loss of biological activity of the growth factor and prevented its internalization, implying that there is only one strongly receptor-dependent, productive way of translocating FGF-1. We also found that the process of translocation did not correlate with the thermal stability of the protein. Additionally, we observed a clear negative correlation between the stability of the FGF-1 mutants and the efficiency of their phosphorylation, which strongly suggests that protein kinases prefer the unfolded state of the protein substrate.

Submission Details

ID: xgTrKxDq3

Submitter: Shu-Ching Ou

Submission Date: Sept. 29, 2018, 11:59 p.m.

Version: 1

Publication Details
Zakrzewska M;Krowarsch D;Wiedlocha A;Olsnes S;Otlewski J,Biochemistry (2006) Structural requirements of FGF-1 for receptor binding and translocation into cells. PMID:17176056
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Fibroblast growth factor 1 P05230 FGF1_HUMAN
100.0 Fibroblast growth factor 1 Q5NVQ3 FGF1_PONAB
97.9 Fibroblast growth factor 1 P34004 FGF1_MESAU
96.4 Fibroblast growth factor 1 P61148 FGF1_MOUSE
96.4 Fibroblast growth factor 1 P61149 FGF1_RAT
97.8 Fibroblast growth factor 1 P20002 FGF1_PIG
92.1 Fibroblast growth factor 1 P03968 FGF1_BOVIN
90.7 Fibroblast growth factor 1 Q7M303 FGF1_SHEEP
91.5 Fibroblast growth factor 1 Q9N1S8 FGF1_CAPCA