Transcriptional regulation of immunoglobulin V genes

The relative transcriptional activity of rearranged and unrearranged (germline) VK genes in secreting plasmacytoma cells was assessed by two independent methods. Measurements of V sequence abundance by hybridization kinetic (Rot) analysis indicated that the steady state content of transcripts from a rearranged VK gene is at least 16,000-fold greater than that from an unrearranged VK gene. Direct measurements of transcriptional activity in isolated nuclei indicated that this difference is due, in large part to a difference in transcription rate. Since the primary sequences of V genes and their 5' flanking regions are not altered during rearrangement, these results suggest that VK gene transcription might be controlled by elements on the 3' side of the VK genes or at the CK locus, perhaps via an influence on chromatin structure.