RNA polymerase 1 L' (DNA-directed RNA polymerase 1 subunit RPA1, RNA polymerase 1 194 kD subunit, RPA194, POLR1A)

Function

• component of the RNA polymerase 1 complex
• largest & catalytic core component of RNA polymerase 1 which synthesizes ribosomal RNA precursors
• forms the polymerase active center together with the 2nd largest subunit
• a single stranded DNA template strand of the promoter is positioned within the central active site cleft of pol 1
• a bridging helix emanates from POLR1A & crosses the cleft near the catalytic site & is thought to promote translocation of pol 1 by acting as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations at each step of nucleotide addition (putative)

nucleoside triphosphate + RNA(n) <--> diphosphate + RNA(n+1)

Structure

• belongs to the RNA polymerase beta' chain family

Compartment

nucleus, nucleolus (putative)

More general terms

• RNA polymerase L'

Component of

• RNA polymerase 1

Database

• UniProt: http://www.uniprot.org/uniprot/O95602.html