Structure and function of haemolysin B,P-glycoprotein and other members of a novel family of membrane translocators.
Recent studies have identified two sub-families of highly conserved polypeptides in a wide variety of organisms concerned with the transport of many different compounds, specific for each transport protein. Both families, represented by HisP and HlyB, respectively, have in common a highly conserved, approximately 25 kD domain, containing an ATP-binding site. The HisP sub-family essentially consists of cytoplasmic proteins which couple energy to the import of small substrates through cytoplasmic membrane permeases in Gram-negative bacteria. The HlyB (P-glycoprotein) sub-family, on the other hand, contains a second large domain which apparently acts as the transmembrane translocator itself, which in most cases drives the secretion of a variety of compounds. These membrane domains share a number of structural features which also serve to distinguish these proteins as a closely related group. Nevertheless, the compounds secreted by the HlyB sub-family include large polypeptides, polysaccharides and a variety of anti-tumour drugs. We describe here the properties of each of these remarkable proteins and we speculate on their possible mechanism of action.
Blight
M A
MA
Department of Genetics, University of Leicester, UK.
Holland
I B
IB
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D006460:Hemolysin Proteins; C050837:Hlyb protein, Bacteria; D008562:Membrane Glycoproteins