title: Antibody for detection and quantitation of membrane-associated folate-binding protein from Lactobacillus casei.
abstract: Lactobacillus casei cells contain a 25 kDa, membrane-associated, folate-binding protein (fbp), which is a component of the folate transport system. Polyclonal antibody to fbp (anti-fbp) has been prepared, and conditions have been established for detection and quantitation of the protein. Anti-fbp did not block [3H]folate transport or binding in L. casei cells. As judged by Western blots, the antibody reacted only with fbp on sodium dodecyl sulfate electrophoretograms of Triton X-100 extracts of L. casei membranes. Anti-fbp showed no cross-reactivity with L. casei dihydrofolate reductase, L. casei 5,10-methenyltetrahydrofolate synthetase, L1210 dihydrofolate reductase, rat liver dihydrofolate reductase, or L1210 folate-binding protein. Enzyme-linked immunosorbent assay measurements indicated the presence of an fbp in membranes of Lactobacillus salivarius and two transport-defective sublines of L. casei. Anti-fbp was used to demonstrate selective extraction, with n-butanol, of fbp from a mixture of Triton-solubilized L. casei membrane proteins; repression of fbp in membranes of L. casei cells grown on high levels of folate; and localization of fbp by electron microscopy, using anti-fbp in conjunction with goat anti-rabbit IgG gold conjugate, in L. casei membranes.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology*; D001692:Biological Transport; D002352:Carrier Proteins / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D002462:Cell Membrane / Q000032:analysis; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000378:metabolism / Q000494:pharmacology; D007780:Lacticaseibacillus casei / Q000032:analysis*; D007939:Leukemia L1210 / Q000378:metabolism; D008854:Microscopy, Electron; D011817:Rabbits; D011956:Receptors, Cell Surface
chemical_list: D000906:Antibodies; D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D005492:Folic Acid