Structure
The three domains of the extracellular portion of GCPII –the protease, apical and C-terminal domains- collaborate in substrate recognition. The protease domain is a central seven-stranded mixed β-sheet. The β-sheet is flanked by 10 α-helices. The apical domain is located between the first and the second strands of the central β-sheet of the protease domain. The apical domain creates a pocket that facilitates substrate binding. The C-terminal domain is an Up-Down-Up-Down four-helix bundle.
The central pocket is approximately 2 nanometres in depth and opens from the extracellular space to the active site. This active site contains two zinc ions. During inhibition, each acts as a ligand to an oxygen in 2-PMPA or phosphate.
There is also one calcium ion coordinated in GCPII, far from the active site. It has been proposed that calcium holds together the protease and apical domains.
In addition, ten glycosylation sites have been identified in human GCPII. Glycosylation far from the catalytic domain still affects the ability of GCPII to hydrolyze NAAG.
Read more about this topic: Glutamate Carboxypeptidase II
Famous quotes containing the word structure:
“A structure becomes architectural, and not sculptural, when its elements no longer have their justification in nature.”
—Guillaume Apollinaire (1880–1918)
“The structure was designed by an old sea captain who believed that the world would end in a flood. He built a home in the traditional shape of the Ark, inverted, with the roof forming the hull of the proposed vessel. The builder expected that the deluge would cause the house to topple and then reverse itself, floating away on its roof until it should land on some new Ararat.”
—For the State of New Jersey, U.S. public relief program (1935-1943)
“The verbal poetical texture of Shakespeare is the greatest the world has known, and is immensely superior to the structure of his plays as plays. With Shakespeare it is the metaphor that is the thing, not the play.”
—Vladimir Nabokov (1899–1977)