CAMs fall into one of four major families: 

• Cadherins

• Immunoglobulin (Ig) superfamily

• Integrins

• Selectins

TLS Online TPP Program

#Id: 4004

#Unit 2. Cellular Organization

S/MARs is a DNA sequence which is generally located between H1 and H3 binding sites.

TLS Online TPP Program

#Id: 4005

#Unit 2. Cellular Organization

Radial loops in metaphase chromosomes. In the radial loop model of metaphase chromosome organization, domains of 30 kb to 100 kb emanate from a central protein scaffold that spirals through the axis of each chromosome arm..

TLS Online TPP Program

#Id: 4007

#Unit 2. Cellular Organization

Matrix-associated regions (MARs) may be identified by characterizing the DNA retained by the matrix isolated in vivo (left) or by identifying the fragments that can bind to the matrix from which all DNA has been removed (right).

TLS Online TPP Program

#Id: 4009

#Unit 2. Cellular Organization

           

TLS Online TPP Program

#Id: 4011

#Unit 2. Cellular Organization

A surprising feature is the lack of conservation of sequence in MAR fragments. They are usually 70% A-T rich. cis-acting sites that regulate transcription are common, as are 5’ introns, and a recognition site for topoisomerase II is usually present in the MAR.

TLS Online TPP Program

#Id: 4016

#Unit 2. Cellular Organization

The nuclear matrix and chromosome scaffold consist of different proteins, although there are some common components. Topoisomerase II is a prominent component of the chromosome scaffold, and is a constituent of the nuclear matrix, suggesting that the control of topology is important in both cases.

SATB1, is a protein that appears to regulate the association of MARs with the matrix in order to regulate transcription of genes in the vicinity of the MAR.