Freeze-fracture studies, terminal

Somljo It is within the measurement errors. There is a fenestration of the SR sheet, and sticking out come the caveolae. No one has really measured accurately this distance, or the distance between the caveolae and SR on top. The surface coupling space is pretty consistent. With regard to what is different in smooth muscle, if you are talking about the SR at the junction having Ca-ATPase or not, we don t know. What we do know from freeze-fracture studies of striated muscle is that the Ca-ATPase does not seem to be at the SR terminal cisternae. We don t know the answer in smooth muscle, but if there is Ca-ATPase at the junctional surface itself, this is different from what one sees in striated muscle. 

Terminal complexes have also been claimed to have been observed in freeze-fracture studies of higher-plant cells. However, at least to the inexperienced eye of this biochemist, the images seen are far less clear than those observed with the algae. Thus far, such complexes have been reported in cells of com roots,78,79 radish roots,80 and cotton... 

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