Allelic forms of mouse transcobalamin 2

Area of Science:

• Genetics
• Biochemistry
• Molecular Biology

Background:

• Transcobalamin 2 (Tcn-2) is the sole identified vitamin B12-binding protein in mouse serum.
• Genetic variations in proteins can influence nutrient transport and metabolism.

Purpose of the Study:

• To characterize the allelic forms of mouse transcobalamin 2.
• To determine the inheritance pattern and genetic basis of Tcn-2 variants in mice.

Main Methods:

• Polyacrylamide gel electrophoresis (PAGE) to analyze protein mobility.
• Interstrain crosses (F1 progeny and backcrosses) to study inheritance patterns.
• Analysis of recombinant inbred lines to assess gene linkage.

Main Results:

• Two distinct electrophoretic forms of mouse Tcn-2 were identified: a slow (Tcn-2s) and a fast (Tcn-2f) migrating variant.
• The slow form was prevalent in 25 inbred strains, while the fast form was found in 3 strains (NZB, ST/bJ, CPB-WV).
• Codominant expression of Tcn-2 alleles was observed in F1 hybrids, with Mendelian inheritance confirmed in backcrosses and recombinant inbred lines.
• The Tcn-2 locus showed no close linkage to numerous tested genetic loci on various chromosomes.

Conclusions:

• Mouse transcobalamin 2 is encoded by a single polymorphic gene locus, proposed as Tcn-2.
• Two codominantly expressed alleles, Tcn-2s and Tcn-2f, determine the electrophoretic variants of Tcn-2.
• The Tcn-2 gene is not closely linked to several other mapped mouse genes, providing a basis for further genetic mapping studies.