TABLE 3.

Comparison of domains between the T7 RNAP and N4 RNAPII

Domaina	Length (aa) in:
	T7 RNAP	N4 RNAPII
N terminus	325	169
Thumb	86	57
Palm	38	39
Palm insertion	78	70
Palm	26	25
Fingers	186	117
Specificity loop	30	27
Fingers	15	10
Palm	54	119
Foot domain	45	40

^aPrediction of domain boundaries in RNAPII is based on sequence alignment to T7 RNAP (Fig. 2) and assignment of domains by Jeruzalmi and Steitz (27).