Cloning immunoglobulin gamma 2b chain gene of mouse: characterization and partial sequence determination.

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Abstract
DNA from newborn mice was digested with restriction endonuclease EcoRI, and a 6,6-kilobase fragment encoding immunoglobulin .gamma.2b chain mRNA derived from MPC 11 myeloma was enriched about 100-fold by RPC-5 column chromatography and agarose gel electrophoresis. The 6.6-kilobase fragment was cloned with .lambda.gt WES .cntdot. .lambda.B as EK2 vector. The cloned phase (.lambda.gt WES .cntdot. IgH22) contained the constant region gene of the .gamma.2b chain but not the variable region gene of MPC 11 mRNA. The constant region genes of the other .gamma. chains (i.e., .gamma.1, .gamma.2a and .gamma.3) were not present in .lambda.gt WES .cntdot. IgH22 DNA. R-loop mapping indicates that the .gamma.2b chain structural gene is divided into 2 parts (330 .+-. 60 SD base pairs and 930 .+-. 110 SD base pairs) by an intervening sequence (360 .+-. 100 SD base pairs). The nucleotide sequence around the junction of the hinge region and CH2 domain was determined and was shown to match the amino acid sequence of the initial part of the CH2 domain of the .gamma.2b chain. The base sequence upstream from the junction is unrelated to the amino acid sequence of the CH1 domain and the hinge region of all the .gamma. chains whose sequences have been determined. The .gamma.2b chain gene is apparently interrupted at the junction of the hinge region and CH2 domain by an intervening sequence. The existence of 2 more intervening sequences, 1 between the CH1 domain and the hinge region and the other between the CH2 and CH3 domains, is discussed.