Polymorphisms in the coding and noncoding regions of murine Pgk-1 alleles

Area of Science:

• Genetics and Molecular Biology
• Biochemistry

Background:

• The mouse X-linked Pgk-1 gene encodes the enzyme phosphoglycerate kinase.
• The Pgk-1b allele, when transfected into human cells, results in detectable mouse PGK-1b enzyme activity.

Purpose of the Study:

• To clone and characterize the mouse Pgk-1a allele.
• To determine the genetic basis for the distinct electrophoretic mobility of PGK-1a compared to PGK-1b.
• To localize the charge variation between the two phosphoglycerate kinase alleles.

Main Methods:

• Cloning of the mouse Pgk-1a allele.
• Construction of DNA recombinants between Pgk-1a and Pgk-1b alleles.
• Transfection of recombinant constructs into human cells.
• Assessment of electrophoretic characteristics of recombinant proteins.
• DNA sequencing of specific exons.

Main Results:

• The charge variation between PGK-1a and PGK-1b was localized to exons 4 or 5.
• A single base-pair difference at codon 155 was identified, predicting lysine (PGK-1b) and threonine (PGK-1a).
• Other DNA sequence polymorphisms, including an L1 repeated element unique to Pgk-1a, were found between the alleles.

Conclusions:

• The distinct electrophoretic mobility of mouse PGK-1a is attributed to a single amino acid difference at codon 155.
• Exons 4 or 5 of the Pgk-1 gene harbor the key determinants for phosphoglycerate kinase allelic variation.
• Sequence analysis reveals multiple polymorphisms contributing to differences between Pgk-1a and Pgk-1b alleles.