REAL GENES, REAL INTELLIGENCE 123ing signaling proteins, will be gene products. But they will have been se-
lected as harmonious members of a dynamic team rather than as
in de pen dent players.Transcription Factors
Th e endpoints of many of these signaling pathways will be gene tran-
scriptions. Th at is when impor tant resources are called up from the genes
at certain times. Th e pro cess is commonly spoken of as the genes being
“turned on” or “switched off ” and then taking over to do their stuff. But
what is really in control is the dynamics of the signaling pro cesses. Th e
involvement of genes then takes further self- organ izing steps.
Th e fi rst of these steps consists of merely gaining access to the genes.
DNA strands containing the genes are heavi ly intertwined with other
proteins (histones) that spool the strands into space- saving units. Th ese
strands fi rst need to be unwound by signaling factors so that other factors
can get at them. It constitutes another layer of regulation/control over
gene transcription and is part of the epige ne tics mentioned earlier.
Even following such access, though, the transcription of genes is no
straightforward matter. It involves a variety of further regulatory com-
ponents: transcription factors, activators, repressors, enhancers, and co-
factors. Correspondingly, the genes have evolved with fl anking regions
on the DNA sensitive to such regulatory factors. Like identity checks to
your online banking accounts, they operate in diff er ent combinations
to further regulate payout (transcription). Th e combination governs
whether transcription will occur at all, and to what degree.
Most prominent in this par tic u lar team are the transcription factors
(TFs). Th ese are proteins that bind to special “promoter” regions fl ank-
ing the DNA sequences and help initiate gene transcription. Th e template
is then read and converted into the transcript. As such, TFs are them-
selves the products of genes and are the fi rst gene products of all the
signaling gossip just mentioned. Th e importance of TFs is seen in that
around 95 percent of genes code for TFs, only 5 percent coding for those
expressed as the structural proteins used in development and metabo-
lism. Unsurprisingly, therefore, the number of TF genes correlates with
the complexity of the organism.
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