>cd00342 gram_neg_porins Porins form aqueous channels for the diffusion of small hydrophillic molecules across the outer membrane. Individual 16-strand anti-parallel beta-barrels form a central pore, and trimerizes thru mainly hydrophobic interactions at the interface. Trimers are stabilized by hytrophillic clamping of Loop L2. Loop 3 bends into the pore, creating an elliptical constriction of about 7 x 11A, large enough to allow passage of a glucose molecule without steric hindrance. Removal of the C-terminal residue (usuallly F) destabilizes the trimer and removal of the 16th beta-sheet abolishes trimerization. Unlike typical membrane proteins, porins lack long hydrophobic stretches. Short turns are found at the smooth, periplasmic end, longer irregular loops are found at the rough, extracellular end. C-terminal residue forms salt bridge with N-terminus.

Probab=97.02 E-value=0.015 Score=30.90 Aligned_cols=141 Identities=16% Similarity=0.132 Sum_probs=69.3 Q ss_pred CCCCCCCCCCCCCCCCCCCCCCCCCEEEEEEEEEEECCCEEEEEEEEEEECCCCC-CCCCCCCCCEEEEEEEEEEEEECC Q ss_conf 5421000122333344667777760268998546404837998451013215556-666212232148999897543127 Q gi|254780598|r 52 DFNGPYAGLSALYNGSFGEEAHHNAGGSIFAGYNVEDSCIMYGVEGDVRYTVPVL-ADNIHSLHGIGGSLRIRGGYEVSD 130 (205) Q Consensus 52 ~w~G~y~g~~~g~~~~~~~~~~~~~~~G~~~GYn~q~~~~V~G~e~d~~~~~~~~-~~~~~~~~~~~~~~~~r~Gy~~~~ 130 (205) T Consensus 139 ~~~Gf~~~a~y~~g~~~~~-~~~~~~~~~~~~Y~~g--~~~~~~~y~~~~~~~~~~~~~~~~~~~--~~~~~ga~Y~~g~ 213 (329) T cd00342 139 FFGGLTFGAMYAFGNQAGS-TSNGRGYGAGLSYENG--PLSLGAAYDQQRNGGGAAGGAAGATSQ--RAYGAGASYDFGG 213 (329) T ss_pred CCCCEEEEEEEECCCCCCC-CCCCCEEEEEEEEECC--CEEEEEEEEEEECCCCCCCCCCCCCCE--EEEEEEEEEEECC T ss_conf 6577899999953667787-7778579999999529--999999999850676444566776514--8999999999689 Q ss_pred CEEEEEEEEEEEEEEEECCCCCCCCCCCEEEEEEEEEEEECCCCCEEEEEEEEEEECCCC---CCCCEEEEEEEEEEC Q ss_conf 677898854477644431345556775204799734661004886799999999750565---566226999998539 Q gi|254780598|r 131 SLLLYATVGPDVAQKYETGKAGEITPIAIGGTAGVGVEVGGLSESLVARLEYRASKYSKV---EGFYNTISLGVGMKF 205 (205) Q Consensus 131 ~~l~Y~~~G~a~~~~~~~~~~~~~~~~~~g~~~G~Gvey~~it~~~~~r~EY~y~df~~~---~~~~~~~~~G~~ykF 205 (205) T Consensus 214 -~--~l~~~Y~~~--~~~~~~~~~~~~~~~~--~~ga~y-~~~~~~~~~~~y~~~~~~~~~~~~~~~~~~~lG~~Y~l 283 (329) T cd00342 214 -L--KLGAGYTNT--RNDNGGGGGSAKFNGY--ELGATY-QLTPALRLGAAYYYTKDRNDGGGDGKANQVALGADYAL 283 (329) T ss_pred -E--EEEEEEEEE--ECCCCCCCCCEEEEEE--EEEEEE-ECCCCEEEEEEEEEEECCCCCCCCCCEEEEEEEEEEEE T ss_conf -9--999999998--8357777875026899--999999-80787389999999944567688897189999999971

HHsearch alignment for GI: 254780598 and conserved domain: cd00342