| Primary Identifier | IPR016392 | Type | Family |
| Short Name | Lg_T_Ag_polyomavir |
| description | The group of polyomaviruses is formed by the homonymous murine virus (Py) as well as other representative members such as the simian virus 40 (SV40) and the human BK and JC viruses []. Their large T antigen (T-ag) protein binds to and activates DNA replication from the origin of DNA replication (ori). Insofar as is known, the T-ag binds to the origin first as a monomer to its pentanucleotide recognition element. The monomers are then thought to assemble into hexamers and double hexamers, which constitute the form that is active in initiation of DNA replication. When bound to the ori, T-ag double hexamers encircle DNA []. T-ag is a multidomain protein that contains an N-terminal J domain, which mediates protein interactions (see , ), a central origin-binding domain (OBD), and a C-terminal superfamily 3 helicase domain (see , ) [].This group represents a large T antigen, Polyomaviridae type.The oncogenic large tumour antigen (LTag) is a protein found in polyomaviruses which is essential for viral DNA replication []. LTag contains three domains, an N-terminal DnaJ domain which mediates protein interactions (), a domain which binds the origin of DNA replication (), and a C-terminal helicase domain. Replication is intitated by LTag assembling at the origin as a double hexamer that distorts and melts the origin DNA [, ]. During elongation LTag acts as a helicase that unwinds duplex DNA at the replication forks []. |
