SMART accession number:SM00392
Description: Binds actin monomers, membrane polyphosphoinositides and poly-L-proline.
Interpro abstract (IPR005455):

This entry represents the Profilin family, which are small eukaryotic proteins that have different functions. In plants, they are major allergens present in pollens [ (PUBMED:21458043) ].

The majority of the Profilin family members binds to monomeric actin (G-actin) in a 1:1 ratio thus preventing the polymerisation of actin into filaments (F-actin). They can also in certain circumstance promote actin polymerisation [ (PUBMED:16542844) ]. However, some Profilin family members, such as Profilin4 from mammals, does not binds to actin and may have functions distinct from regulating actin dynamics [ (PUBMED:19419568) ]. It plays a role in the assembly of branched actin filament networks, by activating WASP via binding to WASP's proline rich domain [ (PUBMED:11137023) ]. Profilin may link the cytoskeleton with major signalling pathways by interacting with components of the phosphatidylinositol cycle and Ras pathway [ (PUBMED:7945274) (PUBMED:1651167) ].

This entry also includes Asgard archaea profilins (Thor profilin, Loki profilin-1 and Loki profilin-2), which bind to actin and regulate the structure of the cytoskeleton. This indicates that Asgard archaea have a functional eukaryotic-like actin machinery [ (PUBMED:30283132) ].

Some Profilins can also bind to polyphosphoinositides such as PIP2 [ (PUBMED:11034907) ]. Overall sequence similarity among profilin from organisms which belong to different phyla (ranging from fungi to mammals) is low, but the N-terminal region is relatively well conserved. The N-terminal region is thought to be involved in actin binding.

GO function:actin binding (GO:0003779)
Family alignment:
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There are 1685 PROF domains in 1683 proteins in SMART's nrdb database.

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