C O N P S
Adenylyl cyclase (AC) is an enzyme located in the plasma membrane of a cell that is important in the regulation of many cellular signals and pathways. AC catalyzes the transformation of ATP to cyclic AMP (cAMP), a second messenger (Purves, 2001; Bowen, 2000).
Click here for the original chime image of adenylyl cyclase
AC is comprised of two catalytic domains, the C1A domain in green and the C2A domain in dark blue (Zhang 1997). Click here to see these domains.
These catalytic domains come together to form a pocket that binds to the G-protein. This protein, especially the pocket, is lined with polar and charged residues, as seen here in white . These polar and charged regions infer that there are ATP binding sites in this region (Zhang 1997).
Both of the catalytic domains contain proteins that assist in the binding of the G protein. To see the GSP in the C1A domain and then the FKP in the C2A domain, click here .
Here are the two catalytic domains, in the green and dark blue, attached to the G-protein subunit, in the Carolina blue. Click here to see the G-protein bound the catalytic domains. Once the G-protein binds to the catalytic domains of the AC protein, the binding sites for ATP are exposed. An enzyme is then able to catalze the transformation of ATP to cAMP, which is then released into the cytoplasm where it continues as the second messsanger in the cell's communication pathway.
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Bowen, R. "Adenylyl Cyclase." Adenylyl Cyclase. 3 Aug. 2000. Accessed 14 Feb. 2005 <http://arbl.cvmbs.colostate.edu/hbooks/molecules/cyclase.html>.
[PDB] Protein Data Bank. 2004. <http://www.rcsb.org/pdb/index.html>. Accessed 06 April 2005.
Purves, William K., David Sadava, Gordon H. Orians, and H. Craig Heller. Life: The Science of Biology. 6th ed. Sunderland: Sinauer Associates, Inc., 2001.
Zhang, G., Liu, Y., Ruoho, A. E. & Hurley, J.H. "Structure of the adenylyl cyclase catalytic core." Nature 386, 247-253 (1997).