Table 1.

Amino acids significantly preferred (-) or avoided (+) at 3' ends of exons across species

Amino acids*†
A	C	D	E	F	G	H	I	K	L4	L2	M	N	P	Q	R4	R2	S4	S2	T	V	W	Y	Species (number of exons)‡
+3		-7		-3			-2	-1		-5		-6	+2		+1	-4		+4					Human (178,438)
+3		-6		-3			-2	-1		-5		-4	+1		+2	-7	+5	+4					Mouse (126,268)
		-4		-5	+3		-1	-2				-6	+2		+1	-3				+4			D. rerio (41,264)
			+4	-1	+3	-6	-2		+5			-3			+1	-4	+2	-5					C. elegans (79,958)
		-6	+3	-2	+4	-8	-3		+5	-5		-1	+6		+2	-7	+1	-4					C. briggsae (74,178)
							-1			-3		-2	+2		+1	-4							A. gambiae (7,930)
				-2	+1		-1			-3				+2									D. melanogaster (48,933)
				-2	+1	-5	-1		-4	+5			+3		+2			+6		+4		-3	A. mellifera (45,426)
					+2		-2		-1						-3	+3				+1			A. thaliana (109,900)
																							S. pombe (2,403)
										-1													S. cerevisiae (417)

*Indices signify rank order of slope coefficients, separately for negative and positive trends. ^†L2, R2, S2 and L4, R4, S4 signify the two-fold and four-fold degenerate blocks of leucine, arginine, and serine, respectively. ^‡S. cerevisiae terminal exons were retained given the small number of genes with more than one intron (eight).