Two types of complexes can be formed between bacteriophage lambda and structures bearing the lambda receptor, either liposomes or rod-shaped particles. Type 1 complexes involve binding between the tip of the lambda tail fiber and the receptor, so that the hollow tail is positioned an average of 17 nm from the surface of the receptor-bearing structures. In type 2 complexes, the hollow tail is in direct contact with the membrane of the liposome or surface of the rod-shaped particle. Type 1 complexes are the precursors for type 2 complexes whose formation is necessary for normal DNA ejection
