Sin3A-associated protein, 30kDa, also known as SAP30, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

which in humans is encoded by the SAP30

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

Function

Histone In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes ...

acetylation : In chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed ''acetate esters'' or simply ''acetates''. Deacetylation is the opposite react ...

plays a key role in the regulation of eukaryotic gene expression. Histone acetylation and deacetylation are catalyzed by multisubunit complexes. The protein encoded by this gene is a component of the

histone deacetylase Histone deacetylases (, HDAC) are a class of enzymes that remove acetyl groups (O=C-CH3) from an ε-N-acetyl lysine amino acid on both histone and non-histone proteins. HDACs allow histones to wrap the DNA more tightly. This is important becaus ...

complex, which includes

SIN3A Paired amphipathic helix protein Sin3a is a protein that in humans is encoded by the ''SIN3A'' gene. Function The protein encoded by this gene is a transcriptional regulatory protein. It contains paired amphipathic helix (PAH) domains, whic ...

SAP18 Histone deacetylase complex subunit SAP18 is an enzyme that in humans is encoded by the ''SAP18'' gene. Function Histone acetylation plays a key role in the regulation of eukaryotic gene expression. Multisubunit complexes catalyze histone acet ...

HDAC1 Histone deacetylase 1 (HDAC1) is an enzyme that in humans is encoded by the ''HDAC1'' gene. Function Histone acetylation and deacetylation, catalyzed by multisubunit complexes, play a key role in the regulation of eukaryotic gene expression. ...

HDAC2 Histone deacetylase 2 (HDAC2) is an enzyme that in humans is encoded by the ''HDAC2'' gene. It belongs to the histone deacetylase class of enzymes responsible for the removal of acetyl groups from lysine residues at the N-terminal region of the ...

, RbAp46,

RbAp48 Histone-binding protein RBBP4 (also known as RbAp48, or NURF55) is a protein that in humans is encoded by the ''RBBP4'' gene. Function This gene encodes a ubiquitously expressed nuclear protein that belongs to a highly conserved subfamily of ...

, and other polypeptides. This complex is active in deacetylating core histone octamers, but inactive in deacetylating nucleosomal histones. A pseudogene of this gene is located on chromosome 3. Mammals have one paralog of SAP30, named SAP30-like ( SAP30L), which shares 70% sequence identity with SAP30. SAP30 and SAP30L together constitute a well-conserved SAP30 protein family. Also SAP30L interacts with several components of the Sin3A corepressor complex and induces transcriptional repression via recruitment of Sin3A and histone deacetylases. Proteins of the SAP30 family (SAP30 proteins) have a functional

nucleolar The nucleolus (; : nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. The nucleolus also participates in the formation of signal recognition particles and plays a ro ...

localization signal and they are able to target Sin3A to the nucleolus. SAP30 proteins have sequence-independent contact with DNA by their N-terminal zinc-dependent module and their acidic central region contributes to histone and nucleosome interactions. The DNA binding of SAP30 proteins is regulated by the nuclear signalling lipids, phosphoinositides (PI). SAP30 proteins provide the first example in which the DNA and PIs seem to stand in a mutually antagonizing interrelationship in regard to their interaction with

zinc finger A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions (Zn2+) which stabilizes the fold. The term ''zinc finger'' was originally coined to describe the finger-like appearance of a ...

proteins and thus exemplifies the molecular mechanism how these lipids can contribute for gene regulation.

Interactions

SAP30 has been shown to interact with: *

, *

Histone deacetylase 2 Histone deacetylase 2 (HDAC2) is an enzyme that in humans is encoded by the ''HDAC2'' gene. It belongs to the histone deacetylase class of enzymes responsible for the removal of acetyl groups from lysine residues at the N-terminal region of the c ...

, *

ING1 Inhibitor of growth protein 1 is a protein that in humans is encoded by the ''ING1'' gene. Function This gene encodes a tumor suppressor protein that can induce cell growth arrest and apoptosis. The encoded protein is a nuclear protein that ph ...

and *

Nuclear receptor co-repressor 1 The nuclear receptor co-repressor 1 also known as thyroid-hormone- and retinoic-acid-receptor-associated co-repressor 1 (TRAC-1) is a protein that in humans is encoded by the ''NCOR1'' gene. NCOR1 is a transcriptional coregulatory protein which c ...

, *

RBBP4 Histone-binding protein RBBP4 (also known as RbAp48, or NURF55) is a protein that in humans is encoded by the ''RBBP4'' gene. Function This gene encodes a ubiquitously expressed nuclear protein that belongs to a highly conserved subfamily of ...

, *

RBBP7 Histone-binding protein RBBP7 is a protein that in humans is encoded by the ''RBBP7'' gene. Function This protein is a ubiquitously expressed nuclear protein and belongs to a highly conserved subfamily of WD-repeat proteins. It is found amon ...

, *

, and * YY1.

Function

Interactions

References

Further reading