Determination of gene product positions in bacteriophage T4 by specific antibody association

Abstract A procedure for locating gene products on the surface of bacteriophage T4D particles by combining immunological methods and electron microscopy is described. Antisera specific for certain gene products were prepared by the absorption of anti-T4 wild-type serum with defective lysates of amber mutants. These lysates lack the products of the mutant genes. Specific regions of the phage particle were found to be associated with antibodies when they were reacted with such absorbed antisera. The locations on the phage surface of antigenic components under the control of seven genes could be demonstrated by this procedure: head proteins (gene 23), tail sheath proteins (gene 18), distal half-fibres (gene 37), middle or joining parts of the two half fibres (gene 36), proximal half fibres (gene 34), structures located at the bottom of the base plate (gene 12) and structures in the region of the head-tail junction (gene 49). The implications of these findings for phage T4 assembly are discussed.