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General secretory pathway (Sec-SRP) complex.  A biphasic pulling force may act on TMSs during translocon-mediated membrane integration (Ismail et al. 2012).  Intermediate structures for the insertion of integral membrane proteins have been visualized (Bischoff et al. 2014).  Insertion of the Type II single span (N-terminus, in, C-terminus, out) protein, RodZ, requires only SecYEG, SecA and the pmf, but not SecB, SecDF, YidC or FtsY (Rawat et al. 2015).  The combined effects of ribosome and peptide binding to SecYEG may allow for co-translational membrane insertion of successive transmembrane segments (Ge et al. 2014). SecA penetrates deeply into the SecYEG channel during insertion, contacting transmembrane helices and periplasmic loops (Banerjee et al. 2017). A partially inserted nascent chain unzips the Sec translocon's lateral gate (Kater et al. 2019). Cardiolipin (CL) is required in vivo for the stability of the bacterial translocon (SecYEG) as well as its efficient function in co-translational insertion into and translocation across the inner membrane of E. coli (Ryabichko et al. 2020). PpiD (623 aas and 1 N-terminal TMS), a peptidyl-prolyl cis-trans isomerase D, and YfgM (206 aas and 1 N-terminal TMS) facilitate the transport of toxins into the E. coli cell in a SecY-dependent process (Jones et al. 2021). Synchronized real-time measurement of Sec-mediated protein translocation has been described (Gupta et al. 2021). An extracellular cutinase from Amycolatopsis mediterranei (AmCut) is able to degrade the plastics, polycaprolactone and polybutylene succinate (Tan et al. 2022). It is secreted from E. coli using the Sec system for export across the inner membrane, and possibly, a non-classical secretion pathway for export across the outer membrane (Tan et al. 2022).

Accession Number:P0AG99
Protein Name:Protein-export membrane protein SecG aka B3175
Molecular Weight:11365.00
Species:Escherichia coli [83333]
Number of TMSs:3
Location1 / Topology2 / Orientation3: Cell inner membrane1 / Multi-pass membrane protein2
Substrate protein polypeptide chain

Cross database links:

RefSeq: AP_003718.1    NP_417642.1   
Entrez Gene ID: 947720   
Pfam: PF03840   
BioCyc: EcoCyc:SECG    ECOL168927:B3175-MONOMER   
KEGG: ecj:JW3142    eco:b3175   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0015450 F:P-P-bond-hydrolysis-driven protein transmem...
GO:0065002 P:intracellular protein transmembrane transport
GO:0009306 P:protein secretion
GO:0043952 P:protein transport by the Sec complex

References (8)

[1] “A novel membrane protein involved in protein translocation across the cytoplasmic membrane of Escherichia coli.”  Nishiyama   8253068
[2] “The dihydropteroate synthase gene, folP, is near the leucine tRNA gene, leuU, on the Escherichia coli chromosome.”  Dallas   8244950
[3] “The complete genome sequence of Escherichia coli K-12.”  Blattner   9278503
[4] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi   16738553
[5] “Disruption of the gene encoding p12 (SecG) reveals the direct involvement and important function of SecG in the protein translocation of Escherichia coli at low temperature.”  Nishiyama   8045257
[6] “Band 1 subunit of Escherichia coli preportein translocase and integral membrane export factor P12 are the same protein.”  Douville   8034620
[7] “A new genetic selection identifies essential residues in SecG, a component of the Escherichia coli protein export machinery.”  Bost   7556084
[8] “Global topology analysis of the Escherichia coli inner membrane proteome.”  Daley   15919996
2AKH   2AKI   3J45   3J46   5MG3   5NCO     

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