Molecular heterogeneity of the 1.0-kb T beta transcript in natural killer and gamma/delta lymphocytes.
The T cell receptor (TcR) beta chain is encoded by a 1.3-kb mRNA which contains variable (V), diversity (D), joining (J) and constant (C) regions. A shorter 1.0-kb transcript with C but no V sequences is found in thymocytes, alpha/beta and gamma/delta T lymphocytes and natural killer cells. The origin, clonal variability and function of this transcript is unknown. We isolated cDNA clones representative of the 1.0-kb mRNA from cDNA libraries of either polyclonal or clonal natural killer and gamma/delta lymphocytes. Ten different types of cDNA clones belonging to three separate groups were identified: (a) "J-C clones" consisting of one of five J beta regions and the corresponding C beta 1 or C beta 2 regions; (b) "D-J-C clones" composed of D beta 1/or D beta 2/J beta rearranged sequences and C beta 1 or C beta 2 sequences; (c) "5'C clones" made up of C beta 1 or C beta 2 regions preceded by the corresponding genomic 5' flanking region. The presence of recombination signal sequences in J-C and D-J-C clones suggests that the first derive from mRNA transcribed from promoters located in the 5' J region and the second from mRNA transcribed from promoters situated in the 5' D region. Nucleotide sequence analysis demonstrated that only three of the ten types of clones isolated had the potential to code a short cytoplasmic T beta protein with a variable D-J beta N terminus. These findings have implications for the mechanisms of T beta germ-line transcription and the function of the T beta transcripts.
Fagioli
M
M
Istituto di Clinica Medica I, University of Perugia, Italy.
Carè
A
A
Ciccone
E
E
Moretta
L
L
Moretta
A
A
Meccia
E
E
Testa
U
U
Falini
B
B
Grignani
F
F
Peschle
C
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000032:analysis; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D011948:Receptors, Antigen, T-Cell / Q000032:analysis* / Q000235:genetics* / Q000502:physiology; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013601:T-Lymphocytes / Q000276:immunology*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D004247:DNA