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= CapZ = From Wikipedia, the free encyclopedia

Functions
This image shows the structures of Cap32/34 superposed onto CapZ (in green) over the Cα positions of the entire CP molecules.[1] In molecular biology CapZ, also known as CAPZ; CAZ1 and CAPPA1, is a protein composed of alpha and beta subunits. It's main function is to cap the barbed (plus) end of actin filaments in cells. It is located in the Z band of the muscle sarcomere, and has also been found in all eukaryotic cells. This protein helps to stabilize the actin filaments protecting it from assembly and disassembly. The activity regulation of this protein can be done by other regulatory proteins that bind to the actin filaments blocking the CapZ, hence allowing assembly.[2]CapZ is also known to play a role in cell signaling as it regulates PKC activity in cardiac cells.

Regulation
Experimentation on chicken muscles have indicated that there are certain proteins inhibit CapZ from binding, including PIP2 and other phospholipids. These molecules bind to CapZ itself to prevent it from binding to actin. However, introduction of certain detergents (in this case Triton X 100) prevent the binding of these molecules to CapZ in turn allowing it to bind to the microfilament. Competition for actin binding sites can also regulate CapZ binding, as seen with filament elongation factors. These factors include like ENA/VASP (enabled/vasodilator-stimulated phosphoprotein). CapZ is not regulated by calcium or calmodulin as seen with other capping proteins, such as Gelsolin.

Cell Movement
CapZ also plays a role in cell movement (cell crawling) by controlling the lengths of microfilaments. When CapZ is inhibited by regulating factors, microfilament polymerization or depolymerization occurs allowing lamellipodia and filopodia to grow out or retract. This gives the cell the appearance of crawling.When CapZ binds, it halts both of these processes.

Cardiac Health
A modest reduction in cardiac CapZ protein protects hearts against acute ischemia-reperfusion injury.[3]

References[edit | edit source]

 * 1) Jump up^
 * 2) Jump up^
 * 3) Jump up^

Genes[edit | edit source]

 * CAPZA1
 * CAPZA2
 * CAPZA3
 * CAPZB

External links[edit | edit source]
Categories:
 * CapZ Actin Capping Protein at the US National Library of Medicine Medical Subject Headings (MeSH)
 * CyMoBase - Database of cytoskeletal and motor protein sequences
 * Cell adhesion proteins
 * Cell biology stubs