Dynamin enzyme. Molecular model of the pleckstrin homology (PH) domain of the dynamin enzyme. Domains are structural regions of enzymes that are often actively involved in biological processes. Dynamin is primarily responsible for facilitating the absorption of material from outside the cell (endocytosis) in eukaryotic cells. Dynamin's PH domain is thought to play an important role in the enzyme's function in endocytosis.