Complete cDNA sequence of the fourth component of murine complement

Area of Science:

• Immunogenetics
• Molecular Biology
• Complement System

Background:

• The fourth component of complement (C4) is a crucial protein in the immune system.
• Understanding C4 gene structure and function is vital for immunology research.

Purpose of the Study:

• To construct complementary DNA (cDNA) clones spanning the entire length of murine complement C4.
• To analyze the nucleotide sequence and deduce the amino acid sequence of mouse C4.
• To compare the murine C4 sequence with human C4 and investigate potential genetic variations within mouse strains.

Main Methods:

• Utilized the Okayama and Berg method for cDNA cloning.
• Sequenced the full-length C4 cDNA from mouse strain B10.WR.
• Performed sequence comparisons between murine and human C4, and between C4 and sex-limited protein (Slp) from different mouse strains.

Main Results:

• Successfully constructed cDNA clones encoding a pre-pro-C4 molecule of 1738 amino acids.
• The murine C4 cDNA sequence exhibits 79% identity to the human C4 cDNA sequence.
• Identified potential structural differences in C4 proteins affecting hemolytic activity and suggested possible genetic exchange between C4 and Slp genes.

Conclusions:

• The study provides a comprehensive sequence of murine C4, aiding in understanding its structure and function.
• Structural variations in C4 may explain differences in hemolytic activity between mouse strains.
• Genetic exchange between C4 and Slp genes is a possibility requiring further investigation.