Table 3.

Intron fragments

	n	Variable	Mean	P
150 Nucleotides at 5' end versus central part of all introns
5' end	36,384	Ki	0.938
Central	36,289	Ki	1.144	< 0.001
5' end	36,384	GC	0.441
Central	36,289	GC	0.432	< 0.001
150 Nucleotides at 3' end versus remainder of all introns
3' end	36,456	Ki	0.924
Central	36,289	Ki	1.144	< 0.001
3' end	36,456	GC	0.410
Central	36,289	GC	0.432	< 0.001
1000 Nucleotides at 5' end versus central part of first introns
5' end	3,295	Ki	1.096
Central	3,306	Ki	1.195	< 0.001
5' end	3,295	GC	0.499
Central	3,306	GC	0.435	< 0.001
150 Nucleotides at 5' end of all introns
Short	14,892	Ki	0.942
Long	21,492	Ki	0.935	0.371 (NS)
Short	14,892	GC	0.459
Long	21,492	GC	0.429	< 0.001
150 Nucleotides at 3' end of all introns
Short	14,929	Ki	0.924
Long	21,527	Ki	0.924	0.991 (NS)
Short	14,929	GC	0.441
Long	21,527	GC	0.389	< 0.001
5' 1000 Nucleotides of first introns
Short	150	Ki	1.193
Long	3,145	Ki	1.092	0.011
Short	150	GC	0.549
Long	3,145	GC	0.499	0.234 (NS)
Central part after removing the 150 nucleotides at 5' and 3' end of all introns
Short	14,014	Ki	1.078
Long	22,275	Ki	1.185	< 0.001
Short	14,014	GC	0.451
Long	22,275	GC	0.420	< 0.001
Central part after removing the 1000 nucleotides at 5' end of first introns
Short	140	Ki	1.172
Long	3,166	Ki	1.196	0.570 (NS)
Short	140	GC	0.457
Long	3,166	GC	0.434	< 0.001
Central part of first introns versus central part of other introns
First	3,306	Ki	1.195
Others	32,012	Ki	1.140	< 0.001
First	3,306	GC	0.435
Others	32,012	GC	0.429	< 0.001

Shown are the average K_i and GC for different fragments of introns. NS, not significant.