A new endocytic model based on the co-rotational grid method

Highlights: • An extended one-dimensional coarse-grained Helfrich model has been proposed. • Both the tensile and bending energy of the plasma membrane is involved. • The axial strain energy is larger than the bending energy near the neck. • Actin forces is the main mechanism driving the invagination of the plasma membrane. -- Abstract: Endocytosis plays important roles in many cellular physiological processes, such as metabolism and immune. Many theoretical models have been proposed to study the endocytic process, but little has considered the tensile deformation of the membrane and the actin forces. In this paper, a new endocytic model is proposed based on the co-rotational grid method. Our model gives a direct estimation of the in-plane strain of the plasma membrane and provides a basis for the calculation of further scission process of the vesicle. The results fit well with experimental data in the literature. Moreover, it is suggested that the active forces of actin at the endocytic site is the main mechanism driving the invagination of the plasma membrane.