Promotes tail assembly by creating a scaffold for the tail tube proteins. Tail assembly proteins G and GT probably wrap the linear tape measure protein to create a tail assembly scaffold. This allows the polymerization of the tail tube protein, during which G and GT are released, therefore they are absent in the mature virion. The tail assembly protein GT is produced by a rare -1 ribosomal frameshift. The ratio of translated G/GT is about 20, and this ratio is important for proper tail assembly. Interacts with the tail assembly protein GT and the tape measure protein. The tail assembly protein GT is produced by a rare -1 ribosomal frameshift. This expression strategy assures a fixed ration of G/GT. Main product of the GT gene, representing 96% of the translated protein. Belongs to the lambda-like tail assembly protein family.