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1.B.21.1.1
Non-specific, 14 β-stranded monomeric OmpG porin (Conlan et al. 2000). pH-induced conformational changes of OmpG have been studied after reconstitution in native E. coli lipids (Mari et al., 2010).  Encoded by a gene in a gene cluster also encoding an ABC sugar uptake system (TC# 3.A.1.1.46), a glucosyl hydrolase and two oxidoreductases.  Therefore it's phsiological function may be glucoside uptake. At neutral/high pH, the channel is open and permeable to substrates of size up to 900Da. At acidic pH, loop L6 folds across the channel and blocks the pore. The channel blockage at acidic pH appears to be triggered by the protonation of a histidine pair on neighboring β-strands, which repel one another, resulting in the rearrangement of loop L6 and channel closure (Köster et al. 2015).  Crystallization and analysis by electron microscopy and X-ray crystallography revealed the fundamental mechanisms essential for the channel activity.  A 28 aa extension has been added to the 14 β-TMS barrel to make a 16 β-TMS barrel with normal activity and stability but differing pH sensitivity (Korkmaz et al. 2015).

Accession Number:P76045
Protein Name:OmpG aka B1319
Length:301
Molecular Weight:34913.00
Species:Escherichia coli [83333]
Location1 / Topology2 / Orientation3: Cell outer membrane1 / Multi-pass membrane protein2
Substrate small molecules

Cross database links:

Genevestigator: P76045
EchoBASE: EB3202
EcoGene: EG13428
eggNOG: NOG132691
HEGENOM: HBG467789
DIP: DIP-10399N
RefSeq: AP_001946.1    NP_415835.1   
Entrez Gene ID: 945889   
Pfam: PF09381   
Drugbank: Drugbank Link   
BioCyc: EcoCyc:G6657-MONOMER    ECOL168927:B1319-MONOMER   
KEGG: ecj:JW1312    eco:b1319   

Gene Ontology

GO:0045203 C:integral to cell outer membrane
GO:0005886 C:plasma membrane
GO:0046930 C:pore complex
GO:0015288 F:porin activity
GO:0006811 P:ion transport

References (4)

[1] “Biochemistry and regulation of a novel Escherichia coli K-12 porin protein, OmpG, which produces unusually large channels.”  Fajardo D.A.et.al.   9721282
[2] “The complete genome sequence of Escherichia coli K-12.”  Blattner F.R.et.al.   9278503
[3] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi K.et.al.   16738553
[4] “Characterization of the RcsC->YojN->RcsB phosphorelay signaling pathway involved in capsular synthesis in Escherichia coli.”  Chen M.H.et.al.   11758943
Structure:
2F1C   2IWV   2IWW   2JQY   2WVP   2X9K   4CTD     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MKKLLPCTAL VMCAGMACAQ AEERNDWHFN IGAMYEIENV EGYGEDMDGL AEPSVYFNAA 
61:	NGPWRIALAY YQEGPVDYSA GKRGTWFDRP ELEVHYQFLE NDDFSFGLTG GFRNYGYHYV 
121:	DEPGKDTANM QRWKIAPDWD VKLTDDLRFN GWLSMYKFAN DLNTTGYADT RVETETGLQY 
181:	TFNETVALRV NYYLERGFNM DDSRNNGEFS TQEIRAYLPL TLGNHSVTPY TRIGLDRWSN 
241:	WDWQDDIERE GHDFNRVGLF YGYDFQNGLS VSLEYAFEWQ DHDEGDSDKF HYAGVGVNYS 
301:	F