Chang Liu


April 2010

Document Type


Degree Name



Dept. of Cell and Developmental Biology


Oregon Health & Science University


Rap1 is a small GTPase of the Ras superfamily, playing important roles in the regulation of many cellular processes, including proliferation, differentiation and adhesion. The activation of Rap1 occurs through exchange of GDP for GTP under the catalysis of a variety of guanine nucleotide exchange factors (GEFs). Our lab previously revealed that different GEFs can dictate different modes of Rap1 activation, which are coupled to downstream pathways differently. My thesis focused on two GEFs for Rap1, exchange proteins directly activated by cAMP (Epac1 and Epac2), and tested the hypothesis that Rap1 activation and signaling can be spatially regulated through targeting of these GEFs to different compartments of the cell. While both Epac1 and Epac2 can be directly activated by cAMP through relief of auto-inhibition, the distinct Ras association (RA) domains in Epac1 and Epac2 confer them specific subcellular locations via interaction with Ran and Ras, respectively. Epac2 has a classical RA




School of Medicine



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