The domain within your query sequence starts at position 2 and ends at position 140; the E-value for the PROF domain shown below is 4.46e-58.

AGWNAYIDSLMADGTCQDAAIVGYKDSPSVWAAVPGKTFVSITPAEVGVLVGKDRSSFFV
NGLTLGGQKCSVIRDSLLQDGEFTMDLRTKSTGGAPTFNVTVTMTAKTLVLLMGKEGVHG
GLINKKCYEMASHLRRSQY

PROF

Profilin

• 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)

There are 1685 PROF domains in 1683 proteins in SMART's nrdb database.

Literature (relevant references for this domain)

Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.

• Sohn RH, Goldschmidt-Clermont PJ
• Profilin: at the crossroads of signal transduction and the actin cytoskeleton.
• Bioessays. 1994; 16: 465-72

Despite its small size, profilin is an amazingly diverse and sophisticated protein whose precise role in cells continues to elude the understanding of researchers 15 years after its discovery. Its ubiquity, abundance and necessity for life in more evolved organisms certainly speaks for its extreme importance in cell function. So far, three ligands for profilin have been well-characterized in vitro: actin monomers, membrane polyphosphoinositides and poly-L-proline. In the years following its discovery, profilin's role in vivo progressed from that of a simple actin-binding protein which inhibits actin polymerization, to one which, as an important regulator of the cytoskeleton, can even promote actin polymerization under the appropriate circumstances. In addition, interactions with components of the phosphatidylinositol cycle and the RAS pathway in yeast implicate profilin as an important link through which the actin cytoskeleton is able to communicate with major signaling pathways.

• Theriot JA, Mitchison TJ
• The three faces of profilin.
• Cell. 1993; 75: 835-8

• Goldschmidt-Clermont PJ, Janmey PA
• Profilin, a weak CAP for actin and RAS.
• Cell. 1991; 66: 419-21

Metabolism (metabolic pathways involving proteins which contain this domain)

% proteins involved	KEGG pathway ID	Description
100.00	map04810	Regulation of actin cytoskeleton

This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with PROF domain which could be assigned to a KEGG orthologous group, and not all proteins containing PROF domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.

Structure (3D structures containing this domain)

3D Structures of PROF domains in PDB

PDB code	Title
1a0k	PROFILIN I FROM ARABIDOPSIS THALIANA
1acf	ACANTHAMOEBA CASTELLANII PROFILIN IB
1awi	HUMAN PLATELET PROFILIN COMPLEXED WITH THE L-PRO10 PEPTIDE
1cf0	HUMAN PLATELET PROFILIN COMPLEXED WITH AN L-PRO10-IODOTYROSINE PEPTIDE
1cjf	PROFILIN BINDS PROLINE-RICH LIGANDS IN TWO DISTINCT AMIDE BACKBONE ORIENTATIONS
1cqa	BIRCH POLLEN PROFILIN
1d1j	CRYSTAL STRUCTURE OF HUMAN PROFILIN II
1f2k	CRYSTAL STRUCTURE OF ACANTHAMOEBA CASTELLANII PROFILIN II, CUBIC CRYSTAL FORM
1fik	HUMAN PLATELET PROFILIN I CRYSTALLIZED IN LOW SALT
1fil	HUMAN PLATELET PROFILIN I CRYSTALLIZED IN HIGH SALT ACTIN-BINDING PROTEIN
1g5u	LATEX PROFILIN HEVB8
1hlu	STRUCTURE OF BOVINE BETA-ACTIN-PROFILIN COMPLEX WITH ACTIN BOUND ATP PHOSPHATES SOLVENT ACCESSIBLE
1k0k	Yeast Profilin, Cubic Crystal Form
1pfl	REFINED SOLUTION STRUCTURE OF HUMAN PROFILIN I
1pne	CRYSTALLIZATION AND STRUCTURE DETERMINATION OF BOVINE PROFILIN AT 2.0 ANGSTROMS RESOLUTION
1prq	ACANTHAMOEBA CASTELLANII PROFILIN IA
1ypr	SACCHAROMYCES CEREVISIAE (YEAST) PROFILIN
2acg	ACANTHAMOEBA CASTELLANII PROFILIN II
2btf	THE STRUCTURE OF CRYSTALLINE PROFILIN-BETA-ACTIN
2jkf	Plasmodium falciparum profilin
2jkg	Plasmodium falciparum profilin
2pav	Ternary complex of Profilin-Actin with the Last Poly-Pro of Human VASP
2pbd	Ternary complex of profilin-actin with the poly-PRO-GAB domain of VASP*
2prf	THREE DIMENSIONAL SOLUTION STRUCTURE OF ACANTHAMOEBA PROFILIN I
2v8c	Mouse Profilin IIa in complex with the proline-rich domain of VASP
2v8f	Mouse Profilin IIa in complex with a double repeat from the FH1 domain of mDia1
2vk3	Crystal structure of rat profilin 2a
3chw	Complex of Dictyostelium discoideum Actin with Profilin and the Last Poly-Pro of Human VASP
3d9y	Crystal Structure of Profilin from Schizosaccharomyces pombe
3dav	Schizosaccharomyces Pombe Profilin crystallized from Sodium formate
3nec	Crystal Structure of Toxoplasma gondii Profilin
3nul	PROFILIN I FROM ARABIDOPSIS THALIANA
3u4l	Cryocooled bovine profilin:actin crystal structure to 2.4 A
3ub5	Profilin:actin with a wide open nucleotide cleft
4d60	4D60
4esp	Crystal Structure of Peanut Allergen Ara h 5
4qwo	4QWO
4x1l	4X1L
4x1m	4X1M
4x25	4X25
5em0	5EM0
5em1	5EM1
5ev0	5EV0
5eve	5EVE
5fds	5FDS
5fef	5FEF
5feg	5FEG

Links (links to other resources describing this domain)

• PROSITE: PROFILIN
• INTERPRO: IPR005455
• PFAM: profilin