Multiple structural genes for mouse amylase.

Area of Science:

• Genetics
• Biochemistry
• Molecular Biology

Background:

• Mouse salivary and pancreatic amylases display genetic variation in structure and quantity.
• This variation is encoded by a gene complex on chromosome 3.
• Key questions involve the genetic basis of amylase diversity and potential separate genes for salivary and pancreatic forms.

Purpose of the Study:

• To investigate whether salivary and pancreatic amylases originate from different structural genes.
• To determine if multiple structural genes contribute to the quantitative variation in each amylase type.
• To elucidate the genetic architecture of amylase production in mice.

Main Methods:

• Comparison of amylase proteins from 12 congenic mouse lines with diverse amylase gene complexes.
• Purification of amylases using affinity chromatography with cyclohepta-amylose.
• Characterization through amino acid composition, specific activity, molecular weight, heat stability, native gel electrophoresis, and peptide mapping (cyanogen bromide cleavage and proteolysis).

Main Results:

• Significant structural differences were observed in pancreatic amylase across mouse strains, not mirrored in salivary amylase.
• A distinct salivary amylase variant was identified.
• Pancreatic amylase exhibited molecular heterogeneity within single strains, while salivary amylase did not.

Conclusions:

• Evidence supports the existence of independent structural genes for salivary and pancreatic amylases.
• At least four distinct structural genes code for pancreatic amylase.
• A single structural gene, separate from pancreatic amylase genes, codes for salivary amylase.