2POR

Here are the secondary structure calculations from the PDB record, as determined by the DSSP method. In the table below, E indicates a beta strand, B indicates a single bridge, S indicates a bend, T indicates a turn, G indicates long 3-helix, and H indicates a long 4-helix (the traditional alpha-helix). Residues without letters have no defined secondary structure.

Sequence and secondary structure
1 EVKLSGDARM GVMYNGDDWN FSSRSRVLFT MSGTTDSGLE FGASFKAHES EEEEEEEEE EEEE SS EE EEEEEEEEEE EEEE TT E EEEEEEGGGH 51 VGAETGEDGT VFLSGAFGKI EMGDALGASE ALFGDLYEVG YTDLDDRGGN HHHTTTSSSE EEEEETTEEE EEES B HHH HHH S T TTT TTS S 101 DIPYLTGDER LTAEDNPVLL YTYSAGAFSV AASMSDGKVG ETSEDDAQEM S SSBTTS S BTTB EEE EEEEETTEEE EEEE SBST TSS B EEE 151 AVAAAYTFGN YTVGLGYEKI DSPDTALMAD MEQLELAAIA KFGATNVKAY EEEEEEEETT EEEEEEEEEE E S TTTS EEEEEEEEEE EETTEEEEEE 201 YADGELDRDF ARAVFDLTPV AAAATAVDHK AYGLSVDSTF GATTVGGYVQ EEEEEEEHHH HHHHTT SS EEEEE EEEEEEEEEE TTEEEEEEEE 251 VLDIDTIDDV TYYGLGASYD LGGGASIVGG IADNDLPNSD MVADLGVKFK EEEETTTEEE EEEEEEEEEE BTTEEEEEE EEEE SSS EEEEEEEEE 301 F

It is clear from the prevalence of E values (the letter denoting strands), that the structure is mainly beta strands. In fact, the PDB record indicates that 56.15% of the protein residues are in beta strands.

The image below is from the PDBSum record, and graphically illustrates the prevalence of beta strands in the protein. PDBSum Secondary Structure Plot

Here is the analysis of the 16 strands in 2POR by PDBSum. This table makes clear the short sides of the barrel vs. the larger sides of the barrel.

Strand No. Start  End   Sheet No.residues Edge   Sequence
---------------------------------------------------------

    1         2    14     A      13       No     VKLSGDARMGVMY            
    2        19    34     A      16       No     WNFSSRSRVLFTMSGT         
    3        40    46     A       7       No     EFGASFK                  
    4        60    65     A       6       No     TVFLSG                   
    5        68    73     A       6       No     GKIEMG                   
    6       118   125     A       8       No     VLLYTYSA                 
    7       128   134     A       7       No     FSVAASM                  
    8       148   158     A      11       No     QEMAVAAAYTF              
    9       161   171     A      11       No     YTVGLGYEKID              
   10       181   192     A      12       No     MEQLELAAIAKF             
   11       195   207     A      13       No     TNVKAYYADGELD            
   12       226   240     A      15       No     AVDHKAYGLSVDSTF          
   13       243   254     A      12       No     TTVGGYVQVLDI             
   14       258   272     A      15       No     DDVTYYGLGASYDLG          
   15       275   284     A      10       No     ASIVGGIADN               
   16       292   301     A      10       No     VADLGVKFKF