TMPDB is a database of experimentally-characterized transmembrane (TM) 
topologies. TMPDB release 6.2 contains a total of 302 TM protein sequences, in 
which 276 are alpha-helical sequences, 17 beta-stranded, and 9 alpha-helical 
sequences with short pore-forming helices buried in the membrane. The TM 
topologies in TMPDB were determined experimentally by means of X-ray 
crystallography, NMR, gene fusion technique, substituted cysteine accessibility 
method, N-linked glycosylation experiment and other biochemical methods. TMPDB 
would be useful as a test and/or training dataset in improving the proposed TM 
topology prediction methods or developing novel methods with higher performance, 
and as a guide for both the bioinformaticians and biologists to better 
understand TM proteins. TMPDB and its subsets are freely available at the 
following web site: http://bioinfo.si.hirosaki-u.ac.jp/~TMPDB/.