Structural component of the 12 appendages that hang from the lower collar. Adhesion protein that binds to the host cell surface during virus attachment and mediates teichoic acids degradation. Binds 1 zinc ion per subunit. Homotrimer. Each appendage is a homotrimer of gp12*. Present in 36 copies in the virion. The N-terminus has three domains that function to attach the appendages to the phage, digest the cell wall teichoic acids, and bind irreversibly to the host. The C-terminus is an autochaperone that aids trimerization. Autocleaved to produce the 74 kDa gp12* assembly attached to the phage particles. Autocleavage of the C-terminus is a posttrimerization event that is followed by an ATP-dependent release.