In vitro reconstitution of a transport complex containing Rab27a, melanophilin and myosin Va

Rab27a and melanophilin (Mlph) are required in vivo to form a melanosome receptor for myosin Va in which Rab27a anchored in the melanosome membrane recruits Mlph, which in turn recruits myosin Va. Here, we show by reconstitution using purified proteins that Rab27a and Mlph are sufficient to form a transport complex with myosin Va in vitro. These results suggest that additional proteins are not required in vivo for assembly of the myosin Va receptor, although other proteins may associate with this tripartite complex to regulate its activity and/or to assist Rab27a in anchoring the complex to the melanosome membrane.