Interaction between t-RNA Conformers. There are many different forms (conformers) of t-RNAs in addition to the canonical "cloverleaf" configuration. The hairpin-like structure (a) is suitable for inter-molecular interactions (horizontal lines) in addition to the numerous intra-molecular Watson-Crick complementary contacts (dots). These interactions can lead to dimerization (b-e) of t-RNAs. A parallel alignment of 3 t-RNAs, for example, (b) de-stabilizes the intra-molecular interactions between bases in the middle t-RNA (c) and unfold it (d) or "zip it" into a dimer (e). The secondary structure of the E. coli tRNA Glu was adopted from  (Left). The schematic structure and interactions of tRNAs are depicted in the right side of the figure. The anticodons are indicated by the boxes and the amino acid by asterisks. The+ - +signs indicate complementary bases.