Common Subunits: RPB5, RPB6, RPB8, RPB10, RPB11, RPB12
As their classification suggests, these subunits are common to all
three nuclear polymerases. The molecular sizes range form 10kDa to
27kDa. Subunits 5, 6, and 8 produce identical results when analyzed
through SDS-polyacrylamide gel mobility, fingerprint patterns, isoelectric
point, and antigenic recognition, no matter the polymerase (Young
1991). Also, it is important to note that RPB12 coelectrophoresed with
RPB10 on SDS gel (Weaver 1999). Kornberg and colleagues were able to
identify the subunit by performing a multi-step purification that revealed
all 12 subunits, as opposed to Young's single step purification that only
eluted 10 subunits. Despite the fact that DNA sequences have failed to
allude to specific function, their conservation suggests that possible
roles may include nucleus localization, processivity, or fidelity of
transcription (Weaver 1999).
Subunits
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