Two large classes of GTPase switch proteins are used in signal transduction pathways:

1. Heterotrimeric G proteins

2. Monomeric G proteins

TLS Online TPP Program

#Id: 809

#Unit 3. Fundamental Processes

In the bacterial genome, the minimum length of promoter that could provide an adequate signal is 12 bp.  The minimum length required for unique recognition increases with the size of genome, a problem in eukaryotic genomes.

TLS Online TPP Program

#Id: 810

#Unit 3. Fundamental Processes

The 12-bp promoter sequence need not be contiguous. 

If a specific number of base pairs separates two constant shorter sequences, their combined length could be less than 12 bp, because the distance of separation itself provides a part of the signal (usually 16-17 bp)

TLS Online TPP Program

#Id: 811

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 812

#Unit 3. Fundamental Processes

-10 and -35 Elements subscript denotes the percent occurrence of the most frequently found base, which varies from 45% to 96%.

TLS Online TPP Program

#Id: 813

#Unit 3. Fundamental Processes

A consensus sequence is, in each case a version of the sequence having at each position the nucleotide (or amino acid) most commonly found. consensus sequence was derived by aligning 300 sequences known to function as s70 promoters and ascertaining the most common base found at each position in the –35 and –10 hexamers.

TLS Online TPP Program

#Id: 814

#Unit 3. Fundamental Processes

Mechanism: How Polymerase Find Promoter Sequences