REGULATION OF THE CYTOSOLIC PSD-95 INTERACTING PROTEIN (CYPIN) AND ITS ROLE IN NEURONAL DENDRITE BRANCHING By

Dendrite morphology regulates how a postsynaptic neuron receives information from presynaptic neurons. The specific patterning of dendrite branches is promoted by extrinsic and intrinsic factors that trigger the activation of functional signaling pathways. However, only a handful of the regulatory factors and biochemical mechanisms involved in determining dendrite morphology are known. The Firestein laboratory previously reported that cypin (cytosolic PSD-95 interactor), the mammalian guanine deaminase (GDA), plays an active role in regulating dendrite branching in hippocampal neurons. Cypin-promoted increases in dendrite number are dependent on binding of zinc ions to cypin and cypin’s guanine deaminase activity. This work focuses on the identification of specific structural properties of cypin that lead to the multifunctional roles in guanine metabolism and dendrite iii development. We first employed phylogenetic analysis and computational structure modeling techniques to construct a three dimensional structural mode