Figure 1.

Model of the actions of ARL2 at distinct sites in cells. ARL2 (green) and TBCD (dark blue) are shown at centrosomes at the top, and free in the cytosol (toward the bottom of the figure), in complex with β-tubulin. The small pool of monomeric ARL2 is in the middle and is the presumptive source of ARL2 that is either imported into mitochondria (left side) or the nucleus (upper right). The role of ARL2 in the folding of the αβ-tubulin heterodimer (red) is depicted, showing α-tubulin bound initially to TBCE, omitting the earlier steps in folding, including the roles of the other tubulin co-chaperones. Also shown here are the proposed 2 distinct pathways inside mitochondria; one involving the ARL2 GAP ELMOD2 and leading to mitochondrial fusion and the other to changes in ATP production through unknown mechanism(s). The yellow bars represent microtubules that may be both regulated by ARL2/TBCD at the centrosome and along which mitochondria traffic, in yet another process influenced by ARL2. See text for details.