Altman:Research

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Department of Physics, Willamette University

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Studying the regulated activity of myosin motors

Motor proteins are molecules in the cell that convert chemical energy into mechanical energy, and are thus important in numerous cellular processes that require generation of motion and force. We investigate myosin, a motor protein superfamily involved in processes such as muscle contraction, cell division, intracellular vesicle transport, and cell migration. We use in vitro and in vivo assays to study the regulated function of a variety of myosins

Single molecule studies of myosins

We are examining the force-sensitivity of Acanthamoeba myosin 1c (AM1C) activity. Class 1 myosins have been split into two subclasses. While subclass 2 myosins are hypothesized to have a force-dependent activity, subclass 1 myosins are not. Two subclass 2 myosins (Rat Myo1b and Mouse Myo1c) have been shown to have a high degree of force-sensitivity, but no subclass 1 myosin has yet been tested. To test the force sensitivity of AM1C, which is from subclass 1, we are using an optical trap, which allows us to apply picoNewton forces to single myosin motors.

We are conducting similar studies of myosin 6 with a mutation associated with hypertrophic cardiomyopathy (HCM) (Myosin 6 H246R). We seek to determine how the H246R mutation alters the chemomechanical cycle of the motor.

Retinal pigment epithelium phagocytosis

Retinal pigment epithelium (RPE) cells phagocytose waste shed by rod photoreceptor cells. This is important for the health of the eye, and failure to complete this process results in retinal degeneration. We study the role of molecular motors in this process. Specifically, we are testing the hypothesis that motor proteins myosin VI and VIIa generate the forces and motion required for the internalization of rod cell debris. To do this, we observe internalization of micron-sized microspheres by a primary RPE cell line (ARPE-19). To perturb the function of a particular myosin, we over-express myosins lacking the motor domain.


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