Required for tail assembly (Probable). Together with FS-gp41, may act as a chaperone mediating the interaction between the tape measure protein (TMP) and the tail tube protein (TTP) thereby directing the polymerization of TTP to form a tail of the correct length (Potential). Expressed in the late phase of the viral replicative cycle. Expression of late genes is activated by the viral late transcription activator C. Produced by conventional translation. Belongs to the mulikevirus tail assembly protein family.