Complete nucleotide sequence of mouse imunoglobulin μ gene and comparison with other immunoglobulin heavy chain genes

摘要

We have determined the complete nucleotide sequence (2168 bases) of the immunoglobulin μ gene cloned from newborn mouse DNA. The cloned l3kh fragment contained the entire constant region gene sequence that in interrupted by three intervening sequences at the junction of domains as previously shown in the γ1, γ2b and α genes. The amino acid sequence predicted by the nucleotide sequence agrees with that of the μ chain secreted by a myeloma MOPC1O4E except for 8 residues out of 448 residues. The homologous domains of the μ, γ1 and γ2b genes are more similar to each other than the different domains of the μ genes are. The result implicates that the class of the immunoglobulin heavy chain genes diverged after the heavy chain genes established the multi-domain structure. The short intervening sequences of the μ and γ genes are more conserved than the coding sequences except for the COOH-terminal domains. The results implicate that the nucleotide sequence of the intervening sequence is under selective pressure, possibly to maintain a secondary structure of the nuclear RNA to be spliced.