Mycoplasma pneumoniae proteins that selectively bind to host cells

Mycoplasma pneumoniae proteins that bind to hamster trachea epithelial cells were identified by incubating 125I-labeled, detergent-solubilized mycoplasmas with glutaraldehyde-fixed host cells. Analysis of the bound fraction by gel electrophoresis and autoradiography revealed that proteins P1, P2, and HMW3 (molecular weights, 165,000, 110,000, and 140,000, respectively), previously implicated in attachment, were among the predominant species. Unlabeled mycoplasma preparations competed with the binding of radiolabeled proteins, suggesting the involvement of a limited number of receptor sites on the host cells.