Mattila…Frolov {Nature 524: 109}

A hemi-fission intermediate links two mechanistically distinct stages of membrane fission. Nature. 2015 Aug 6;524(7563):109-13. doi: 10.1038/nature14509.
Dynamin1 produces fission of the endocytic vesicle neck in two mechanistically distinct steps: radial constriction of the neck (step 1) causes hemi-fission while subsequent elongation of the neck (step 2) leads to complete fission.