期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：3
页码：1800-1804
DOI：10.1073/pnas.78.3.1800
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：From a library of mouse sperm DNA, we have isolated two overlapping clones which contain the C{delta} gene. One of these clones also contains the C{micro} gene. The C{delta} gene is separated from the C{micro} membrane exons by approximately 2 kilobases (kb) of DAN. The C{delta} gene was identified by (a) hybridization to poly(A)+RNA prepared from the IgD-producing rat plasma cell tumor IR731, and (b) homology of a translated nucleotide sequence to the amino acid sequence of the human {delta} chain. The C{delta} gene spans 8 kb of DNA in the germ line. Plasmid subclones of the C{delta} gene were used as probes in Southern and RNA blot experiments. RNA blot analysis of cytoplasmic poly(A)+RNA from IR731 and a {micro}+{delta}+ B-cell hybridoma revealed 1.6- and 2.7-kb {delta} mRNA species with different 3' ends, which presumably encode the secreted and membrane-bound forms, respectively, of the {delta} chain. Southern blot analysis of DNA from two {micro}+{delta}+ lymphomas revealed that the C{delta} gene is in the germ-line configuration in each case. Restriction map analysis of C{micro} and C{delta} genomic clones isolated from a library of normal {micro}+{delta}+ B-cell DNA also gave no evidence for DNA rearrangement in the region between the C{micro} and C{delta} genes. Taken together, these data suggest that IgD expression in {micro}+{delta}+ B cells does not involve a VH-to-C{delta} DNA switch rearrangement. We propose that simultaneous expression of C{delta} and C{delta} with a single VH gene is mediated by two alternative routes of RNA processing of a primary nuclear transcript which contains the VH, C{micro
