This domain is named PAZ after the proteins Piwi Argonaut and Zwille. This domain is found in two families of proteins that are involved in post-transcriptional gene silencing. These are the Piwi family and the Dicer family, that includes the Carpel factory protein. The function of the domains is unknown but has been suggested to mediate complex formation between proteins of the Piwi and Dicer families by hetero-dimerisation. The three-dimensional structure of this domain has been solved [2-4]. The PAZ domain is composed of two subdomains. One subdomain is similar to the OB fold, albeit with a different topology. The OB-fold is well known as a single-stranded nucleic acid binding fold. The second subdomain is composed of a beta-hairpin followed by an alpha-helix. The PAZ domains shows low-affinity nucleic acid binding and appears to interact with the 3' ends of single-stranded regions of RNA in the cleft between the two subdomains. PAZ can bind the characteristic two-base 3' overhangs of siRNAs, indicating that although PAZ may not be a primary nucleic acid binding site in Dicer or RISC, it may contribute to the specific and productive incorporation of siRNAs and miRNAs into the RNAi pathway.
This domain is named after the proteins Piwi Argonaut and Zwille. It is also found in the CAF protein from Arabidopsis thaliana. The function of the domain is unknown but has been found in the middle region of a number of members of the Argonaute protein family, which also contain the Piwi domain (INTERPRO) in their C-terminal region [PUBMED:12906857]. Several members of this family have been implicated in the development and maintenance of stem cells through the RNA-mediated gene-quelling mechanisms associated with the protein DICER.
Cerutti L, Mian N, Bateman A; , Trends Biochem Sci 2000;25:481-482.: Domains in gene silencing and cell differentiation proteins: the novel PAZ domain and redefinition of the Piwi domain. PUBMED:11050429 EPMC:11050429 .
Song JJ, Liu J, Tolia NH, Schneiderman J, Smith SK, Martienssen RA, Hannon GJ, Joshua-Tor L; , Nat Struct Biol 2003;10:1026-1032.: The crystal structure of the Argonaute2 PAZ domain reveals an RNA binding motif in RNAi effector complexes. PUBMED:14625589 EPMC:14625589 .