Table 1. Criteria for searching U6 and U4 snRNA candidates in Giardia:

U-snRNA	Features
U6-snRNA	5′-stem-loop
	ISL with a bulged uridine, likely to be located below a “C-A” wobble pair
	ACAGAG motif
	AGC invariant tri-nucleotide
	Base-pairing with U2-snRNA on 5′ and 3′ of the ISL
U4-snRNA	GCT tri-nucleotide which base pairs with “AGC” tri-nucleotide of U6
	5′-sequence which base-pairs with U6 central region and sequence immediately after “GCT” which base-pairs with U6 near its 5′-stem-loop
	Sm-protein binding site (usually starts with ‘A’ followed by a number of ‘U’s and terminates with ‘G’)