scholarly journals Transforming growth factor alpha: an aromatic side chain at position 38 is essential for biological activity.

1989 ◽  
Vol 9 (2) ◽  
pp. 860-864 ◽  
Author(s):  
E Lazar ◽  
E Vicenzi ◽  
E Van Obberghen-Schilling ◽  
B Wolff ◽  
S Dalton ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Disulfide Bonds ◽  
Transforming Growth Factor ◽  
Site Directed Mutagenesis ◽  
Side Chain ◽  
Transforming Growth Factor Alpha ◽  
Aromatic Side Chain ◽  
Factor Alpha ◽  
Alpha Gene

Site-directed mutagenesis has been performed in the human transforming growth factor alpha gene. When tyrosine 38 is mutated into phenylalanine or tryptophane, biological activity is retained. In contrast, other alterations between cysteine 34 and cysteine 43 and disruption of disulfide bonds 8 to 21 and 34 to 43 resulted in loss of activities. The presence of an aromatic side chain at position 38 of transforming growth factor alpha seems to be essential for its activity.

Transforming growth factor alpha: an aromatic side chain at position 38 is essential for biological activity

1989 ◽  
Vol 9 (2) ◽  
pp. 860-864
Author(s):  
E Lazar ◽  
E Vicenzi ◽  
E Van Obberghen-Schilling ◽  
B Wolff ◽  
S Dalton ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Disulfide Bonds ◽  
Transforming Growth Factor ◽  
Site Directed Mutagenesis ◽  
Side Chain ◽  
Transforming Growth Factor Alpha ◽  
Aromatic Side Chain ◽  
Factor Alpha ◽  
Alpha Gene

Site-directed mutagenesis has been performed in the human transforming growth factor alpha gene. When tyrosine 38 is mutated into phenylalanine or tryptophane, biological activity is retained. In contrast, other alterations between cysteine 34 and cysteine 43 and disruption of disulfide bonds 8 to 21 and 34 to 43 resulted in loss of activities. The presence of an aromatic side chain at position 38 of transforming growth factor alpha seems to be essential for its activity.

scholarly journals Substitution of lysine for arginine at position 42 of human transforming growth factor-alpha eliminates biological activity without changing internal disulfide bonds.

1989 ◽  
Vol 9 (9) ◽  
pp. 4083-4086 ◽  
Author(s):  
D Defeo-Jones ◽  
J Y Tai ◽  
G A Vuocolo ◽  
R J Wegrzyn ◽  
T L Schofield ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Receptor Binding ◽  
Disulfide Bonds ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Receptor Interaction ◽  
Composition Analysis ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

Transforming growth factor-alpha (TGF-alpha) is a growth-promoting protein that binds to the epidermal growth factor (EGF) receptor. To identify critical residues that govern TGF-alpha-EGF receptor binding, we prepared site-specific substitution mutants of TGF-alpha. Mutant proteins were tested in receptor-binding and mitogenesis assays. Semiconservative substitutions at positions 4, 12, 18, and 45 decreased biological activity 2.1- to 14-fold. The conservative substitution of lysine for arginine at position 42 completely eliminated biological activity. Amino acid composition analysis of proteolytic fragments from TGF-alpha and the Lys-42 mutant indicated that these proteins contained the same disulfide bonds. These studies suggest that arginine 42 may be a contact point for TGF-alpha-EGF receptor interaction.

Substitution of lysine for arginine at position 42 of human transforming growth factor-alpha eliminates biological activity without changing internal disulfide bonds

1989 ◽  
Vol 9 (9) ◽  
pp. 4083-4086
Author(s):  
D Defeo-Jones ◽  
J Y Tai ◽  
G A Vuocolo ◽  
R J Wegrzyn ◽  
T L Schofield ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Receptor Binding ◽  
Disulfide Bonds ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Receptor Interaction ◽  
Composition Analysis ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

Transforming growth factor-alpha (TGF-alpha) is a growth-promoting protein that binds to the epidermal growth factor (EGF) receptor. To identify critical residues that govern TGF-alpha-EGF receptor binding, we prepared site-specific substitution mutants of TGF-alpha. Mutant proteins were tested in receptor-binding and mitogenesis assays. Semiconservative substitutions at positions 4, 12, 18, and 45 decreased biological activity 2.1- to 14-fold. The conservative substitution of lysine for arginine at position 42 completely eliminated biological activity. Amino acid composition analysis of proteolytic fragments from TGF-alpha and the Lys-42 mutant indicated that these proteins contained the same disulfide bonds. These studies suggest that arginine 42 may be a contact point for TGF-alpha-EGF receptor interaction.

scholarly journals Transforming growth factor alpha: mutation of aspartic acid 47 and leucine 48 results in different biological activities.

1988 ◽  
Vol 8 (3) ◽  
pp. 1247-1252 ◽  
Author(s):  
E Lazar ◽  
S Watanabe ◽  
S Dalton ◽  
M B Sporn
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Amino Acid ◽  
Growth Factor ◽  
Aspartic Acid ◽  
Transforming Growth Factor ◽  
Biologically Active ◽  
Single Amino Acid ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

To study the relationship between the primary structure of transforming growth factor alpha (TGF-alpha) and some of its functional properties (competition with epidermal growth factor (EGF) for binding to the EGF receptor and induction of anchorage-independent growth), we introduced single amino acid mutations into the sequence for the fully processed, 50-amino-acid human TGF-alpha. The wild-type and mutant proteins were expressed in a vector by using a yeast alpha mating pheromone promoter. Mutations of two amino acids that are conserved in the family of the EGF-like peptides and are located in the carboxy-terminal part of TGF-alpha resulted in different biological effects. When aspartic acid 47 was mutated to alanine or asparagine, biological activity was retained; in contrast, substitutions of this residue with serine or glutamic acid generated mutants with reduced binding and colony-forming capacities. When leucine 48 was mutated to alanine, a complete loss of binding and colony-forming abilities resulted; mutation of leucine 48 to isoleucine or methionine resulted in very low activities. Our data suggest that these two adjacent conserved amino acids in positions 47 and 48 play different roles in defining the structure and/or biological activity of TGF-alpha and that the carboxy terminus of TGF-alpha is involved in interactions with cellular TGF-alpha receptors. The side chain of leucine 48 appears to be crucial either indirectly in determining the biologically active conformation of TGF-alpha or directly in the molecular recognition of TGF-alpha by its receptor.

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