Bruce J. Schnapp

Learn More
The cargo that the molecular motor kinesin moves along microtubules has been elusive. We searched for binding partners of the COOH terminus of kinesin light chain, which contains tetratricopeptide repeat (TPR) motifs. Three proteins were found, the c-jun NH(2)-terminal kinase (JNK)-interacting proteins (JIPs) JIP-1, JIP-2, and JIP-3, which are scaffolding(More)
Do biological motors move with regular steps? To address this question, we constructed instrumentation with the spatial and temporal sensitivity to resolve movement on a molecular scale. We deposited silica beads carrying single molecules of the motor protein kinesin on microtubules using optical tweezers and analysed their motion under controlled loads by(More)
Several enzyme complexes drive cellular movements by coupling free energy-liberating chemical reactions to the production of mechanical work. A key goal in the study of these systems is to characterize at the molecular level mechanical events associated with individual reaction steps in the catalytic cycles of single enzyme molecules. Ideally, one would(More)
Kinesin, a mechanoenzyme that couples ATP hydrolysis to movement along microtubules, is thought to power vesicle transport and other forms of microtubule-based motility. Here, microscopic silica beads were precoated with carrier protein, exposed to low concentrations of kinesin, and individually manipulated with a single-beam gradient-force optical particle(More)
In many organisms, pattern formation in the embryo develops from the polarized distributions of messenger RNAs (mRNAs) in the egg. In Xenopus, the mRNA encoding Vg1, a growth factor involved in mesoderm induction, is localized to the vegetal cortex of oocytes. A protein named Vera was shown to be involved in Vg1 mRNA localization. Vera cofractionates with(More)
In the budding yeast Saccharomyces cerevisiae, the spindle pole body (SPB) serves as the microtubule-organizing center and is the functional analog of the centrosome of higher organisms. By expressing a fusion of a yeast SPB-associated protein to the Aequorea victoria green fluorescent protein, the movement of the SPBs in living yeast cells undergoing(More)
Single microtubules from squid axoplasm support bidirectional movement of organelles. We previously purified a microtubule translocator (kinesin) that moves latex beads in only one direction along microtubules. In this study, a polar array of microtubules assembled off of centrosomes in vitro was used to demonstrate that kinesin moves latex beads from the(More)
We used the accumulation of constitutively active kinesin motor domains as a measure of where kinesins translocate in developing neurons. Throughout development, truncated Kinesin-3 accumulates at the tips of all neurites. In contrast, Kinesin-1 selectively accumulates in only a subset of neurites. Before neurons become polarized, truncated Kinesin-1(More)
BACKGROUND Cytoplasmic mRNA localization is a widespread mechanism for restricting the translation of specific mRNAs to distinct regions of eucaryotic cells. This process involves specific interactions between cellular factors and localization signals in the 3' untranslated regions of the localized mRNA. Because only a few of these cellular factors have(More)
A reconstituted system for examining directed organelle movements along purified microtubules has been developed. Axoplasm from the squid giant axon was separated into soluble supernatant and organelle-enriched fractions. Movement of axoplasmic organelles along MAP-free microtubules occurred consistently only after addition of axoplasmic supernatant and(More)