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Understanding diffusion and trafficking in mammalian cells with particle tracking

Event Details

Event Dates: 

Monday, October 15, 2012 - 10:00am

Speaker Name(s): 

Diego Krapf

Speaker Affiliation(s): 

Colorado State University
Seminar Type/Subject

Event Details & Abstract: 

Kv2.1 is unusual among voltage-gated K+ channels in that it localizes to micron-sized clusters on the cell surface of neurons. Within these clusters, Kv2.1 is non-conducting. I will discuss single-molecule tracking experimental results showing that these surface structures are specialized platforms involved in the trafficking of membrane proteins to and from the cell surface. This study is the first to identify stable cell surface platforms dedicated to ion channel trafficking. Multi-color TIRF-based studies indicate that fluorescently labeled K+ channel containing vesicles directly tether to and deliver cargo in a discrete fashion to the Kv2.1 surface clusters. We find that retrieval of Kv2.1 from the membrane occurs also at the cluster perimeter, via a clathrin-mediated endocytic pathway. The internalization of Kv2.1 channels is often aborted because the channel escapes from the endocytic pit. However, when a channel is captured by a clathrin-coated pit it is temporarily immobilized. Interestingly, these stalling events introduce an anomalous subdiffusion process and weak ergodicity breaking in the plasma membrane, that is, the ensemble and time averages do not coincide.