Is dynamin really a 'pinchase'?

The motivation for this article was a recent conversation with an author of a major cell-biology textbook who was gratified that the problem of 'pinching off' membrane vesicles from donor membranes had been solved. It was now known, the author claimed, that the large GTPase dynamin was a 'pinchase' severing the necks of budding vesicles. We are concerned that this appealing speculation has been prematurely elevated to cell-biological dogma. Furthermore, by seeing dynamin exclusively as a pinchase we might fail to recognize alternative functions. In this article, we review briefly the evidence that dynamin is a pinchase, discuss some problems with that speculation and show that other possible functions for dynamin may be at least as appealing.