In chloroplasts, transcription of plastid genes is mediated by two types of RNA polymerase: plastid-encoded RNA polymerase (PEP) and nuclearencoded RNA polymerase (NEP) . Transcription in plastids is also mediated by a number of nuclear-encoded factors in addition to PEP and NEP. In the insoluble RNA polymerase preparation samples, a total of 18 components named as pTACs (pTAC1 to pTAC18) were identified. pTAC8 (AT2G46820) is one of the components associated with PEP complex.pTAC8 is also termed as CURT1B, TMP14, and PsaP.
