Which myosin type is responsible for intracellular cargo transport?
Intracellular cargo trafficking covers both microtubule and actin routes. Long range 10 to 100 micron interphase transport uses kinesin dynein on microtubules, while short range local transport within cortical actin rich zones 1 to 10 micron uses myosin. Processive myosin capable of multiple steps without dissociation required for efficient transport. Myosin V class features high duty ratio spending about 70 percent cycle strongly attached, dimeric coiled coil tail, six IQ motifs with calmodulin light chains per head forming long 24 nanometer lever arm achieving 36 nanometer step matching helical repeat of actin, hand over hand walking mechanism with gating coordinated by intramolecular strain. Transport cargos include melanosomes via interaction with melanophilin Rab27a in melanocytes, synaptic vesicles, endoplasmic reticulum and mRNA in budding yeast via Myo2 Myo4. Myosin I monomeric membrane tether, myosin II bipolar contractile filaments for cytokinesis low duty ratio non processive, myosin VI minus end directed for endocytosis. Therefore myosin V primary dedicated motor for processive intracellular cargo transport along actin cables and cortical networks.
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 17: Myosin V and Cargo Transport.