Molecular cloning and nucleotide sequence of a cDNA clone coding for the cell attachment domain in human fibronectin.

A cDNA clone coding for the cell attachment domain in human fibronectin has been isolated using synthetic oligonucleotides. Three sets of mixed tetradecamer oligonucleotides were synthesized based on amino acid sequences in the 108-amino acid cell attachment domain (Pierschbacher, M. D., Ruoslahti, E., Sundelin, J., Lind, P., and Peterson, P. A. (1982) J. Biol. Chem. 257, 9593-9597). One of these sets was made complementary to amino acids located near the COOH terminus of the cell attachment domain and synthesized as a mixture of 24 sequences. This oligonucleotide mixture was used to prime cDNA synthesis with mRNA prepared from a human fibrosarcoma as a template. A cDNA library was constructed with the oligonucleotide-primed sequences in the vector pBR322. Colonies that hybridized with the primer were isolated from the library and further identified by hybridization with oligonucleotides deduced from an amino acid sequence located 45 amino acid residues NH2-terminal of the primer sequence. One clone which hybridized to both probes was characterized in detail. The insert was 380 base pairs long and its nucleotide sequence agreed completely with the corresponding amino acid sequence of human plasma fibronectin, showing that the sequences for this region are identical in plasma fibronectin and fibronectin from a cell line. This clone should be useful for studies on the expression of fibronectins and may also allow for the production of the biologically active cell attachment domain of fibronectin in bacteria.