Transcription

The transcription of one strand of DNA into a
complementary RNA molecule is the first step
in gene expression. Multiple proteins (called
transcription factors) form a transcription complex,
which binds to DNA. Although there are
differences in transcription in prokaryotes and
eukaryotes, much of the basic process is the
same. Transcription is catalyzed by RNA polymerase.
RNA polymerase in E. coli has five subunits
(two !, two ", and one sigma), each encoded
by its own genes. RNA polymerases in
eukaryotes are complex (see p. 214). Eukaryotic
RNA polymerase consists of three different
enzymes, which transcribe different types of
genes.