Transport of membrane-bound organelles is critical to neuronal cell function yet mechanisms hitching vesicles to transport machinery remain elusive. Here we test whether jun-kinase interacting protein (JIP-1), a peripheral membrane scaffolding protein that binds kinesin light chain, is sufficient to mediate cargo transport in axons and study its competition with amyloid precursor protein cytoplasmic domain (APP-) and negative charge, also known motor receptors. Fluorescent beads (100 nm diameter) exhibit sequence-specific fast anterograde transport (0.46μm/s instantaneous velocity) in the squid giant axon when conjugated to a 14- amino acid synthetic peptide derived from the carboxyl terminus of JIP-1. JIP-1- beads have statistically significant faster velocities, longer run lengths, and fewer pauses of shorter durations than APP-C or negatively charged beads by cumulative probability analyses of thousands of motile beads compared by a nonparametric K-S test, with a P=0.004. In competition experiments negatively charged beads gradually cease moving when co-injected with either APP-C or JIP-1 beads, which sustain 90% motility. Co-injection of APP-C and JIP-1 beads decreases each bead's propensity to move initially. At later time points JIP-1-beads recover frequency without further decreasing APP-C moves, suggesting JIP-1 recruits motors from a cryptic pool not accessible to APP-C. Soluble JIP-1 peptide inhibits JIP-1 beads, with smaller effects on APP-C and negatively charged beads. Thus the hierarchy for recruitment of transport machinery is JIP>APP>negative charge. Organelle transport may in part be regulated through the numbers, types and affinities of motor receptors displayed on each organelle's cytoplasmic surface.
"Axonal Transport, JIP-1, APP-C"
INCBN IGERT and the NIH
Level of Degree
Biomedical Sciences Graduate Program
First Committee Member (Chair)
Second Committee Member
Third Committee Member
Fourth Committee Member
Fifth Committee Member
Seamster, Pamela. "Spatiotemporal dynamics of transport in the squid giant axon : competition between cargo motor receptors, JIP-1, APP-C, and negative charge." (2011). http://digitalrepository.unm.edu/biom_etds/45