Molecular motors are proteins that transform chemical energy into mechanical work, generating forces that lead to motion. We are studying myosin V, a processive molecular motor involved in intracellular transport and found in many animal cell types, particularly neurones. It has two heads that bind to an actin filament and a long neck region that attaches to its cargo, such as vesicles and organelles. The myosin molecule walks hand-over-hand along the actin track via the coordinated binding and release of its heads, fuelled by the hydrolysis of ATP. We use energetics to model the interaction of external load and intramolecular strain with the chemical cycle that governs the stepping action of myosin V, focusing on information transmission between its two heads.  We are currently deriving analytical results for the expected motor velocity and run length in various classes of discrete stochastic stepping cycle models, and using these to compare different myosin V stepping models against available experimental data. A further project models the movement of RNA polymerase during DNA transcription as a soliton.