Comparison of mRNA precursors in plasmacytomas producing closely related kappa chains.
To help elucidate the mechanisms of formation and expression of active immunoglobulin genes, we have made a systematic study of the processing patterns of the mRNAs that code for a closely related family of kappa chains. Among the members of this family, represented by the V(kappa)21 group of plasmacytomas, are examples in which six different germ-line V genes are joined to four different J segments in various combinations. The mRNA precursors were identified by hybridizing a cloned kappa-cDNA probe to poly(A)-containing nuclear RNAs that were size fractionated on methylmercury-agarose gels and transferred to diazotized paper. Based on the length of the segment excised in the last detectable processing step, which presumably represents the removal of the J-C intron, the precursor patterns were classified into four primary categories that correlated well with the type of J segment being expressed. The J segments were thus located at distances ranging from 2.4 to 4.8 kilobases from the constant-region gene. Different V genes joined to the same J segment exhibited similar precursor patterns, suggesting that the size of the translocated V segment may be relatively uniform among members of the V(kappa)21 group. A large (9.1 kilobases) component, which is likely to represent a primary transcription product, was observed in all processing categories, regardless of which J segment was being utilized. This surprising observation leads to some interesting predictions about the mechanism of V-J translocation.
D000818:Animals; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D007942:Leukemia, Experimental / Q000235:genetics / Q000276:immunology; D051379:Mice; D008970:Molecular Weight; D009194:Myeloma Proteins / Q000235:genetics; D009694:Nucleic Acid Precursors / Q000235:genetics*; D010954:Plasmacytoma / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics*
D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D009194:Myeloma Proteins; D009694:Nucleic Acid Precursors; D012333:RNA, Messenger