HlyBHlyDTolC

HlyBHlyDTolC is a designation used in some genomic and proteomic annotation efforts to refer to a hypothetical multi-domain transporter protein found in several Gram-negative bacteria. The label is used mainly in in silico contexts, and there is no experimentally characterized protein by this exact name.

The name suggests a fusion or compositional assembly reminiscent of the classical type I secretion system components HlyB, HlyD, and TolC; however, no published experimental study confirms a single polypeptide combining these elements.

Predicted architecture from computational analyses often includes domains related to ATPase activity (HlyB-like), periplasmic adaptor function (HlyD-like), and outer-membrane channel attributes (TolC-like). Predictions vary between methods, and many databases flag the entry as uncertain or potentially misannotated.

Possible function, if real, would be involvement in substrate transport across the cell envelope, analogous to type I secretion systems, but no substrate, interaction partners, or secretion activity has been demonstrated.

Genomic context shows occasional adjacency to other secretion-related genes, with sporadic distribution across taxa; the name is largely confined to annotation catalogs rather than curated databases. See also: HlyB, HlyD, TolC, Type I secretion system.