No conventional function for the conventional kinesin?

A paper by DeGiorgis et al. (DeGiorgis JA, Petukhova TA, Evans TA, Reese TS. Kinesin-3 is an organelle motor in the squid giant axon. Traffic 2008; DOI: 10.1111/j.1600-0854.2008.00809.x) in this issue of Traffic reports on the identification and function of a second squid kinesin, a kinesin-3 motor. As expected, the newly discovered motor associates with axoplasmic organelles in situ and powers motility along microtubules of vesicles isolated from squid axoplasm. Less expected was the finding that kinesin-3 may be the predominant motor for anterograde organelle movement in the squid axon, which challenges the so far undisputed view that this function is fulfilled by the conventional kinesin, kinesin-1. These novel findings let us wonder what the real function of kinesin-1--the most abundant motor in squid axons--actually is.