GP9 and infection: The six gp10 trimers are a crucial component of the baseplate and structural analysis of this protein has revealed its role in extension of the short tail fibers encoded by gp12 by means of a partner shift: the pre-infection state sees an interaction between the C-terminal end of gp10 and gp12, while infection requires an interaction between the baseplate protein gp9 and gp10 so as to release the short tail fibers, thus permitting interaction with the host receptor [13].