Chemically synthesised human immunodeficiency virus P7 nucleocapsid protein can self-assemble into particles and binds to a specific site on the tRNA(Lys,3) primer.

The zinc-bound form of the human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein, p7, aggregates into particles visible by electron microscopy. The HIV primer tRNA(Lys,3) forms similar high molecular weight complexes with p7 that are also detected by gel mobility shift assays. RNA oligonucleotides of the three stem-loop structures in tRNA(Lys,3) were assayed for the competitive inhibition of p7-tRNA(Lys,3) binding by the intensities of free tRNA(Lys,3) bands on native gels. This reveals that the p7 binds specifically to the central domain of tRNA(Lys,3) where the D and T psi C loops come together, but not the anticodon stem-loop.