The domain within your query sequence starts at position 3 and ends at position 184; the E-value for the SIR2 domain shown below is 5.3e-57.

GAGISTPSGIPDFRSPGSGLYSNLQQYDIPYPEAIFELGFFFHNPKPFFMLAKELYPGHY
RPNVTHYFLRLLHDKELLLRLYTQNIDGLERASGIPASKLVEAHGTFVTATCTVCRRSFP
GEDIWADVMADRVPRCPVCTGVVKPDIVFFGEQLPARFLLHMADFALADLLLILGTSLEV
EP

SIR2

SIR2
PFAM accession number:PF02146
Interpro abstract (IPR003000):

The sirtuin (also known as Sir2) family is broadly conserved from bacteria to human. Yeast Sir2 (silent mating-type information regulation 2), the founding member, was first isolated as part of the SIR complex required for maintaining a modified chromatin structure at telomeres. Sir2 functions in transcriptional silencing, cell cycle progression, and chromosome stability [(PUBMED:7498786)]. Although most sirtuins in eukaryotic cells are located in the nucleus, others are cytoplasmic or mitochondrial.

This family is divided into five classes (I-IV and U) on the basis of a phylogenetic analysis of 60 sirtuins from a wide array of organisms [(PUBMED:10873683)]. Class I and class IV are further divided into three and two subgroups, respectively. The U-class sirtuins are found only in Gram-positive bacteria [(PUBMED:10873683)]. The S. cerevisiae genome encodes five sirtuins, Sir2 and four additional proteins termed 'homologues of sir two' (Hst1p-Hst4p) [(PUBMED:7498786)]. The human genome encodes seven sirtuins, with representatives from classes I-IV [(PUBMED:10873683),(PUBMED:15128440)].

Sirtuins are responsible for a newly classified chemical reaction, NAD-dependent protein deacetylation. The final products of the reaction are the deacetylated peptide and an acetyl ADP-ribose [(PUBMED:11747420)]. In nuclear sirtuins this deacetylation reaction is mainly directed against histones acetylated lysines [(PUBMED:11722841)].

Sirtuins typically consist of two optional and highly variable N- and C- terminal domain (50-300 aa) and a conserved catalytic core domain (~250 aa). Mutagenesis experiments suggest that the N- and C-terminal regions help direct catalytic core domain to different targets [(PUBMED:11722841), (PUBMED:10381378)].

The 3D-structure of an archaeal sirtuin in complex with NAD reveals that the protein consists of a large domain having a Rossmann fold and a small domain containing a three-stranded zinc ribbon motif. NAD is bound in a pocket between the two domains [(PUBMED:11336676)].

GO function:NAD+ binding (GO:0070403)

This is a PFAM domain. For full annotation and more information, please see the PFAM entry SIR2