Table 1.

Ysc secretion apparatus

ProteinSize (kDa)FeaturesaLocalization in bacteriaaRole in Yop secretionaReference(s)
YscA3.8Hydrophobic C-terminal domainUnknown 228,296
YscB15.4UnknownNT 228
YscC67.1Signal sequence of 26 residues; member of the secretin family; forms pores of 200 Å with a central channel of 50 ÅOM+ 194, 228
YscD46.7Hydrophobic domain (aa 120–130)IM+ 228, 265
YscE7.4Hydrophobic C-terminal domainUnknown+ 8, 228
YscF9.4Unknown+ 8, 228
YscG12.9Hydrophobic N-terminal domainC/M+ 8, 228, 265
YopR18.3Encoded byyscH Secreted 8, 228
YscI12.6Unknown+ 8, 228
YscJ27.0Lipoprotein; hydrophobic C-terminal domain followed by 3 positively charged residues; previously called YlpBUnknown+ 8, 64, 228
YscK23.9One hydrophobic domainUnknown+ 8, 228
YscL24.9Unknown+ 228, 326
YscM1/LcrQ12.3Resembles YscM2 and YopHSecreted 8, 228, 327
YscN47.8Contains Walker box A and B; putative ATPaseIM/C+ 24, 93, 375
YscO19.0Secreted+ 24, 93, 252
YscP50.4Secreted+ 24, 93, 252a,326a
YscQ34.4Unknown+ 24,93
YscR24.4Four transmembrane domains and a large central cytoplasmic regionIM+ 24, 93
YscS9.6Two putative transmembrane domainsUnknown (probably IM)+ 24, 93, 261
YscT28.4Six putative transmembrane domainsUnknown (probably IM)NT 24, 93
YscU40.3Four transmembrane domains at the N terminus with a large cytoplasmic C-terminal regionIM+ 9, 24,93
YscX13.6Unknown+ 170a
YscY13.1Unknown+ 170a
LcrD/YscV77.8Eight potential transmembrane domains; hydrophobic N-terminal half; hydrophilic C terminus predicted to protrude into the cytoplasmIM+ 263
VirG/YscW14.6Lipoprotein ancillary to YscC secretinProbably OM+ (YopB, YopD, LcrV) 7
  • a IM, inner membrane; OM, outer membrane; C, cytosolic; M, membrane-associated protein; NT, not tested; +, required for secretion; −, not required for secretion; aa, amino acids.