Major histocompatibility complex class I (MHC-I) molecules signal infection or transformation by engaging receptors on T lymphocytes. The spatial organization of MHC-I on the plasma membranes is important for this engagement. We and others have shown that MHC-I molecules, like other membrane proteins, are not uniformly distributed, but occur in patches in the plasma membrane. Here, we describe the temporal details of MHC-I patch formation and combine them with the spatial details, which we have described earlier, to yield a comprehensive quantitative description of patch formation. MHC-I is delivered to the plasma membrane in clathrin-coated vesicles, arriving at a rate of ∼2.5×10−3 μm−1 min−1 (or about two arrivals per minute over the whole cell). The vesicles dock and fuse at non-random, apparently targeted, locations on the membrane and the newly delivered MHC-I molecules form patches that are a few hundred nanometers in diameter. The patches are maintained at steady state by a dynamic equilibrium between the rate of delivery and the rate of hindered diffusion of MHC-I molecules out of the patches (caused by components of the actin cytoskeleton).
The authors declare no competing or financial interests.
D.B. performed the experiments, wrote the algorithms, analyzed the data, interpreted the experiments and wrote the manuscript. M.E. provided the fibroblast cells, provided experimental advice and support, and contributed to writing the manuscript. L.A.G. provided experimental advice, wrote the manuscript and provided funding support.
The authors gratefully acknowledge a grant from the United States-Israel Binational Science Foundation [grant number 2009345]; this work was also partially supported by the Focal Technological Area program of the Israeli National Nanotechnology Initiative (INNI).
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.187112.supplemental
- Received February 4, 2016.
- Accepted July 21, 2016.
- © 2016. Published by The Company of Biologists Ltd