Definition
Nectofibrins are 'anti-fibronectin' peptides. By interacting with this Arg-Gly-Asp-Ser region, both peptides efficiently inhibit the binding of fibronectin to its receptors. Antibodies produced against the nectofibrins recognize the fibronectin receptor molecule and can be used in characterization studies1.
Related peptides
Nectofibrin sequences were deduced from the cDNA strands of the human and rat fibronectin cell binding domain1.
Discovery
Peptides encoded by cDNA strands might form amphiphilic structures and bind one another. In 1987, Brentani RR et al used this approach to study the interaction between fibronectin (FN) and its cell receptor. Taking into consideration the nucleotide sequence from published rat cDNA clones that correspond to the cell binding site (Arg-Gly-Asp-Ser) in the FN molecule, they found that the amino acid sequence for the putative receptor binding site was Trp-Thr-Val-Pro-Thr-Ala. Binding of labeled FN to receptor-rich MG63 human osteosarcoma cells was inhibited by the hexapeptide. The hexapeptide Gly-Ala-Val-Ser-Thr-Ala predicted similarly from the nucleotide sequence of human FN was equally efficient in such inhibition. These peptides were named "anti-FN" peptides or "nectofibrins"1.
Structural Characteristics
Comparison of the hydropathies of nectofibrin hexapeptides Trp-Thr-Val-Pro-Thr-Ala and Gly-Ala-Val-Ser-Thr-Ala predicted from the nucleotide sequences of cloned rFN (rat FN) and hFN (human FN), respectively, shows that the difference in hydropathy between them is only 6.0% of the total possible difference. The hexapeptides bear little relation to actual amino acid sequences on the receptor molecule but rather mimic a "conformational" binding site1.
Mode of Action
Nectofibrins, by interacting with the cell binding domain of fibronectin, the Arg-Gly-Asp-Ser region, efficiently inhibit the binding of fibronectin to its receptors1.
Functions
Nectofibrins were first synthesized and used to gain an insight into the chemical nature of receptor binding sites of FN and for the characterization of such sites on receptor molecules1.
References
1.Brentani RR, Ribeiro SF, Potocnjak P, Pasqualini R, Lopes JD, Nakaie CR. (1988). Characterization of the cellular receptor for fibronectin through a hydropathic complementarity approach. PNAS., 85(2):364-367.
