Four related EGF receptors participate in signaling by the many members of EGF family :

In the mouse - Erb-B1, 2, 3, and 4

In humans - HER 1, 2, 3, and 4

TLS Online TPP Program

#Id: 3968

#Unit 2. Cellular Organization

Each domain consists of -40 kilobases of DNA, or may be smaller, 10 kb each. About -400 domains in the E. coli genome. The ends of the domains appear to be randomly distributed instead of located at predetermined sites on the chromosome.

TLS Online TPP Program

#Id: 3969

#Unit 2. Cellular Organization

An unrestrained supercoil in the DNA path creates tension, but no tension is transmitted along DNA when a supercoil is restrained by protein binding.

TLS Online TPP Program

#Id: 3970

#Unit 2. Cellular Organization

Chromosomal packaging is maintained by supercoiling of DNA in case of bacteria

TLS Online TPP Program

#Id: 3971

#Unit 2. Cellular Organization

Because supercoiled DNA molecules are more compact than relaxed molecules, they migrate more rapidly during gel electrophoresis

TLS Online TPP Program

#Id: 3972

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 3974

#Unit 2. Cellular Organization

E. coli has at least four individual topoisomerases (I through IV). Those of type I (topoisomerases I and III) generally, relax DNA by removing negative supercoils (increasing Lk).