Role Of Neurogranin In The Regulation Of Calcium Binding To Calmodulin

Author

Anuja Chandrasekar, The University of Texas Graduate School of Biomedical Sciences at HoustonFollow

Date of Graduation

5-2013

Document Type

Thesis (MS)

Program Affiliation

Neuroscience

Degree Name

Masters of Science (MS)

Advisor/Committee Chair

M.Neal Waxham

Committee Member

Ruth Heidelberger

Committee Member

Harel Z Shouval

Committee Member

John A Putkey

Committee Member

Vasanthi Jayaraman

Abstract

Role of Neurogranin in the regulation of calcium binding to Calmodulin

Anuja Chandrasekar, B.S

Advisor: M. Neal Waxham, Ph.D

The overall goal of my project was to gain a quantitative understanding of how the interaction between two proteins neurogranin (RC3) and calmodulin (CaM) alters a fundamental property of CaM. CaM, has been extensively studied for more than four decades due to its seminal role in almost all biological functions as a calcium signal transducer. Calcium signals in cardiac and neuronal cells are exquisitely precise and enable activation of some processes while down-regulating others. CaM, with its four calcium binding sites, serves as a central component of calcium signaling in these cells. It is aided in this role as a regulatory hub that differentially activates targets in response to a calcium flux by proteins that alter its calcium binding properties.

Neurogranin, also known as RC3, is a member of a family of small neuronal IQ (SNIQ) domain proteins that was originally thought to play a ‘capacitive’ role by sequestering CaM until a calcium influx of sufficient intensity arrived. However, based on earlier work in our lab on neurogranin, we believe that this protein plays a more nuanced role in neurons than simply acting as a CaM buffer. We believe that neurogranin is one of the proteins which, by altering the kinetics of calcium binding allow CaM to decode a variety of signals with fine precision. To quantify the interaction between CaM, neurogranin and calcium, I used biophysical techniques and computational simulations. From my results, I conclude that neurogranin finely regulates the proportion of calcium-saturated CaM and thereby directs CaM’s target specificity.

Keywords

Calmodulin, Neurogranin, Calcium, Isothermal Titration Calorimetry, fluorimetry, ODE simulation model