# This is the famous tetrahymena self_splicing intron described
by T. Chech & colleagues.  The base pairing list is among the
first ones posed.  Later ones invoke another pseudoknot.
The interesting thing about the pseudoknot of this listing
is that it allows for a variety of back stacking. The stems
comprising the pseudoknot each have a  branching loop containing
some stems other than that of the pseudoknot.  These can be used
for "internal backstacking" with the stems comprising the pseudoknot.
Those external to the pseudoknot  can be used for "external
backstacking". 

> TTintron1
cucucuAAAU AGCAAUAUUU ACCUUU
GGAGGGAAAA GUUAUCAGGC AUGCACCUGG UAGCUAGUCU UUAAACCAAU AGAUUGCAUC
GGUUUAAAAG GCAAGACCGU CAAAUUGCGG GAAAGGGGUC AACAGCCGUU CAGUACCAAG
UCUCAGGGGA AACUUUGAGA UGGCCUUGCA AAGGGUAUGG UAAUAAGCUG ACGGACAUGG
UCCUAACCAC GCAGCCAAGU CCUAAGUCAA CAGAUCUUUU GUUGAUAUGG AUGCAGUUCA
CAGACUAAAU GUCGGUCGGG GAAGAUGUAU UCUUCUCAUA AGAUAUAGUC GGACCUCUCC
UUAAUGGGAG CUAGCGGAUG AAGUGAUGCA ACACUGGAGC CGCUGGGAAC UAAUUUGUAU
GCGAAAGUAU AUUGAUUAGU UUUGGAGUAC UCGuaag

$List1
1 32
2 31
3 30
4 29
5 28
6 27
7 26
8 25
9 24
36 61
37 60
38 59
39 58
40 57
41 56
42 55
43 54
44 53
45 52
63 98
64 97
65 96
66 95
67 94
68 93
69 91
70 90
71 89
72 88
73 87
74 86
75 85
76 84
101 283
102 282
103 281
104 280
105 279
107 277
108 276
112 219
113 218
114 217
115 216
116 214
117 213
122 209
123 208
124 207
125 206
126 205
127 204
132 200
133 199
134 198
135 197
137 196
138 195
139 194
140 188
141 187
142 186
143 185
144 184
147 166
148 165
149 164
150 163
151 162
152 161
153 160
154 159
170 180
171 179
172 178
220 263
221 262
225 258
226 257
227 256
228 255
232 252
233 251
234 250
235 249
236 248
237 247
238 246
239 245
267 317
269 316
270 315
271 314
272 313
273 312
285 303
286 302
287 301
288 300
289 299
290 298
291 297
318 418
319 417
321 336
322 335
323 334
325 333
326 332
337 372
338 371
339 370
340 369
341 368
342 367
343 366
347 361
348 360
349 359
350 358
374 407
375 406
376 405
377 404
378 403
379 402
380 401
381 400
384 397
385 396
386 395
387 394
388 393
