The coat protein A precursor (gp3) (minor coat protein) (424 aas and two TMSs, one N-terminal and one C-terminal) (Identical to gp3 or pIII of enterobacterial phage fd).  It is involved in the late stage of filamentous phage translocation mediated by multiple interactions with each individual component of the host TolQRA proton-pore complex (TC# 2.C.1.2.1) (Pellegri et al. 2023).