PRC2 is one of the two classes of Polycomb-group proteins

Polycomb-group proteins

Polycomb-group proteins are a family of proteins first discovered in fruit flies that can remodel chromatin such that epigenetic silencing of genes takes place...

 or (PcG). The other component of this group of proteins is PRC1.

This complex has Histone

Histone

In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...

 Methyltransferase

Methyltransferase

A methyltransferase is a type of transferase enzyme that transfers a methyl group from a donor to an acceptor.Methylation often occurs on nucleic bases in DNA or amino acids in protein structures...

 activity and primarily trimethylates histone H3 on lysine

Lysine

Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....

 27 (i.e. H3K27me3) , a mark of transcriptionally silent chromatin

Chromatin

Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene...

. PRC2 is required for initial targeting of genomic region (PRC Response Elements or PRE) to be silenced, while PRC1 is required for stabilizing this silencing

Gene silencing

Gene silencing is a general term describing epigenetic processes of gene regulation. The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic modification...

 and underlies cellular memory

Cellular memory

Cellular memory can refer to:*A variation of body memory, the pseudoscientific hypothesis that memories can be stored in individual cells*A memory card used in cellphones...

 of silenced region after cellular differentiation

Cellular differentiation

In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...

. These protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s are required for long term epigenetic silencing of chromatin and have an important role in stem cell

Stem cell

This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...

 differentiation and early embryo

Embryo

An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

nic development. PRC2 are present in all multicellular organism

Multicellular organism

Multicellular organisms are organisms that consist of more than one cell, in contrast to single-celled organisms. Most life that can be seen with the the naked eye is multicellular, as are all animals and land plants.-Evolutionary history:Multicellularity has evolved independently dozens of times...

s.

The mouse PRC2 has four subunits: Suz12 (zinc finger

Zinc finger

Zinc fingers are small protein structural motifs that can coordinate one or more zinc ions to help stabilize their folds. They can be classified into several different structural families and typically function as interaction modules that bind DNA, RNA, proteins, or small molecules...

), Eed , Ezh2 (SET domain with histone methyltransferase activity) and RbAp48 (histone binding domain

Binding domain

A binding domain is a protein domain which binds to a specific atom or molecule, such as calcium or DNA. Upon binding, proteins may undergo a conformational change. Binding domains are essential for the function of many proteins....

)

PRC2 have a role in X chromosome

X chromosome

The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...

 inactivation, in maintenance of stem cell fate, in imprinting. Aberrant expression of PRC2 has been observed in cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

.