Serum response factor (SRF) is a key transcriptional activator of the c-fos gene and of muscle-specific gene expression. We have identified four forms of the SRF coding sequence, SRF-L (the previously identified form), SRF-M, SRF-S and SRF-I, that are produced by alternative splicing. The new forms of SRF lack regions of the C-terminal transactivation domain by splicing out of exon 5 (SRF-M), exons 4 and 5 (SRF-S) and exons 3, 4 and 5 (SRF-I). SRF-M is expressed at similar levels to SRF-L in differentiated vascular smooth-muscle cells and skeletal-muscle cells, whereas SRF-L is the predominant form in many other tissues. SRF-S expression is restricted to vascular smooth muscle and SRF-I expression is restricted to the embryo. Transfection of SRF-L and SRF-M into C2C12 cells showed that both forms are transactivators of the promoter of the smooth-muscle-specific gene SM22α, whereas SRF-I acted as a dominant negative form of SRF.
Research Article| January 25 2000
Four isoforms of serum response factor that increase or inhibit smooth-muscle-specific promoter activity
Paul R. KEMP;
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Paul R. KEMP, James C. METCALFE; Four isoforms of serum response factor that increase or inhibit smooth-muscle-specific promoter activity. Biochem J 1 February 2000; 345 (3): 445–451. doi: https://doi.org/10.1042/bj3450445
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