TABLE 1.

Amino acid sequence of the GGQ-containing heptapeptide of eRF1

Amino acid	m/za
	Recombinant eRF1		Endogenous eRF1
	b ion	y ion	b ion	y ion
Gly	58.03		58.03
Gly	115.05	631.50	115.05	645.37
Glnb	243.03	574.52	257.20	588.42
Ser	330.16	446.32	344.16	446.33
Ala	401.26	359.24	415.21	359.34
Leu	514.17	288.25	528.19	288.30
Arg		175.12		175.12

^am/z values for the missing ions in the MS detection are in italics.

^bThe residue is methylated.