: a cellular protein found especially in microfilaments (such as those comprising myofibrils) and active in muscular contraction, cellular movement, and maintenance of cell shape
variants
or actini-
or actino-
1
: having a radiate form
actinolite
2
: actinic radiation (such as X-rays)
actinometer
Examples of actin in a Sentence
Recent Examples on the Web
New Atlas, 2 Nov. 2024
In healthy muscle, small threadlike components called actin and myosin neatly line up next to each other.
—Cindy Kuzma, SELF, 29 Oct. 2024
Those cells reveal some eukaryote-like features (opens a new tab), such as a cytoskeleton built with the protein actin.
—Quanta Magazine, 28 Oct. 2024
One color shows the cell nucleus (to mark where each cell is) and others show the structural component actin (which determines the shape of the cell) and the microtubules that are part of the communication and transport network within a cell.
—Eva Amsen, Forbes, 17 Oct. 2024
Dormant NSCs in Drosophila have a protrusion that extends from the cell body; the researchers had recently demonstrated that the protrusion is enriched with actin microfilaments.
—New Atlas, 15 Aug. 2024
The arrangement of actin within cells is regulated by another type of protein called formin, which accelerates the assembly of a particular actin, filamentous actin (f-actin).
—New Atlas, 15 Aug. 2024
Rome proposes that vaults might be ferrying the blueprint for actin to the construction sites.
—Betsy Hanson, Discover Magazine, 11 Nov. 2019
One place where vaults seem to clump together is where the cell is building long fibers of the protein actin that make up part of the cell’s internal skeleton.
—Betsy Hanson, Discover Magazine, 11 Nov. 2019
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Noun
In turn, the cytoskeleton relies on a type of actin protein, called filamentous or F-actin.
—New Atlas, 2 Nov. 2024
In healthy muscle, small threadlike components called actin and myosin neatly line up next to each other.
—Cindy Kuzma, SELF, 29 Oct. 2024
Those cells reveal some eukaryote-like features (opens a new tab), such as a cytoskeleton built with the protein actin.
—Quanta Magazine, 28 Oct. 2024
One color shows the cell nucleus (to mark where each cell is) and others show the structural component actin (which determines the shape of the cell) and the microtubules that are part of the communication and transport network within a cell.
—Eva Amsen, Forbes, 17 Oct. 2024
Dormant NSCs in Drosophila have a protrusion that extends from the cell body; the researchers had recently demonstrated that the protrusion is enriched with actin microfilaments.
—New Atlas, 15 Aug. 2024
The arrangement of actin within cells is regulated by another type of protein called formin, which accelerates the assembly of a particular actin, filamentous actin (f-actin).
—New Atlas, 15 Aug. 2024
Rome proposes that vaults might be ferrying the blueprint for actin to the construction sites.
—Betsy Hanson, Discover Magazine, 11 Nov. 2019
One place where vaults seem to clump together is where the cell is building long fibers of the protein actin that make up part of the cell’s internal skeleton.
—Betsy Hanson, Discover Magazine, 11 Nov. 2019
Dictionary Entries Near actin
Cite this Entry
“Actin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/actin. Accessed 22 Nov. 2024.
Copy CitationKids Definition
actin
noun
ac·tin
ˈak-tən 
: a protein of muscle that with myosin is active in muscular contraction
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