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Chicken glucagon: sequence and potency in receptor assay.
1Solomon A. Berson Research Laboratory, Veterans Administration Medical Center, Bronx, NY.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|November 1, 1987
Summary
Chicken glucagon differs from mammalian forms at position 28, with asparagine replaced by serine. However, chicken glucagon shows similar receptor binding activity to porcine glucagon.
Area of Science:
- Biochemistry
- Comparative Endocrinology
- Molecular Biology
Background:
- Glucagon is a highly conserved 29-amino acid peptide hormone.
- Mammalian glucagons are largely similar, with guinea pig glucagon being a notable exception due to differences in its COOH-terminus.
- Previous studies reported amino acid content and partial sequencing of chicken glucagon.
Purpose of the Study:
- To purify and determine the complete amino acid sequence of chicken glucagon.
- To compare the sequence of chicken glucagon with known mammalian glucagon sequences.
- To assess the functional similarity of chicken glucagon to mammalian glucagon using a receptor assay.
Main Methods:
- Purification of chicken glucagon.
- Complete amino acid sequencing of purified chicken glucagon.
- Rat liver receptor binding assay to compare chicken and porcine glucagon activity.
Main Results:
- The complete amino acid sequence of chicken glucagon was determined.
- Chicken glucagon differs from typical mammalian glucagon by a single amino acid substitution: asparagine at position 28 is replaced with serine.
- Chicken glucagon demonstrated indistinguishable activity from porcine glucagon in the rat liver receptor assay.
Conclusions:
- Chicken glucagon exhibits a unique amino acid sequence compared to most mammalian glucagons.
- Despite sequence variation, chicken glucagon retains functional similarity to mammalian glucagon in receptor interaction.
- This suggests potential evolutionary divergence in glucagon structure without complete loss of function.