Figure 1

Schematic of experiments to probe the role that crosslinking plays in the mechanics and mobility of actin-microtubule composites. (a) Cartoon of molecular components comprising actin-microtubule composites with varying crosslinker motifs (None, Actin, Microtubule, Both, Co-linked, Both 2x) described in the text. The calculated length between crosslinkers for each motif is listed under each cartoon, where l_c,a is the length between crosslinkers along an actin filament, l_c,m is the length between crosslinkers along a microtubule, and l_c is the length between crosslinkers when actin and microtubules are linked to each other. (b) Two-color laser scanning confocal micrograph of 5.8 µM Co-linked actin-microtubule composite with ~3% of actin and microtubules labeled with Alexa-488 (green) and rhodamine (red), respectively. (c) Sample microrheology data for a Co-linked composite, showing the stage displacement (purple) and the force measured for an individual trial (black) before (dark grey region), during (light grey region) and after (white region) the stage displacement. Inset: Cartoon of optical tweezers microrheology measurement. An optically trapped 4.5 µm diameter microsphere (not drawn to scale) embedded in a crosslinked composite is displaced 10 µm (x, purple) at a speed of 10 µm/s while the corresponding force the composite exerts is measured (F, black).