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An array of tandem repeats is defined as several (at least two) adjacent copies having the same or similar sequence motifs. These periodic sequences are generated by internal duplications in both coding and non-coding genomic sequences. Repetitive units of protein tandem repeats are considerably diverse, ranging from the repetition of a single amino acid to domains of 100 or more residues.[1][2]
Distribution in proteomes[edit]
Tandem repeats are ubiquitous in proteomes and occur in at least 14% of all proteins.[3] For example, they are present in almost every third human protein and even in every second protein from Plasmodium falciparum or Dictyostelium discoideum.[3][4] Tandem repeats with short repetitive units (especially homorepeats) are more frequent than others.[3]
Structure of tandem repeats[edit]
Approximately half of the tandem repeat regions has intrinsically disordered conformation being naturally unfolded.[5][6][7] The other half of the regions with the stable 3D structure has a plethora of shapes and functions.[8][9] Depending on the length of the repetitive units, their protein structures can be subdivided into five classes:[8]
- crystalline aggregates formed by regions with 1 or 2 residue long repeats
- fibrous structures stabilized by inter-chain interactions with 3-7 residue repeats
- structures with the repeats of 5–40 residues dominated by solenoid proteins
- closed (not elongated) structures with the repeats of 30-60 residue long
- beads on a string structures with typical size of repeats over 50 residues, which are already large enough to fold independently into stable domains.
Functions of proteins with tandem repeats[edit]
Some well-known examples of proteins with tandem repeats are collagen, which plays a key role in the arrangement of the extracellular matrix; alpha-helical coiled coils having structural and oligomerization functions; leucine-rich repeat proteins, which specifically bind a number of globular proteins by their concave surfaces; and zinc-finger proteins, which regulate the expression of genes by binding DNA.
References[edit]
Category:Biochemistry Category:Proteins Category:Protein structural motifs
- ^ Heringa, Jaap (1998). "Detection of internal repeats: how common are they?". Current Opinion in Structural Biology. 8 (3): 338–345. doi:10.1016/s0959-440x(98)80068-7. ISSN 0959-440X.
- ^ Andrade, Miguel A; Ponting, Chris P; Gibson, Toby J; Bork, Peer (2000). "Homology-based method for identification of protein repeats using statistical significance estimates". Journal of Molecular Biology. 298 (3): 521–537. doi:10.1006/jmbi.2000.3684. ISSN 0022-2836.
- ^ a b c Marcotte, Edward M.; Pellegrini, Matteo; Yeates, Todd O.; Eisenberg, David (1999). "A census of protein repeats". Journal of Molecular Biology. 293 (1): 151–160. doi:10.1006/jmbi.1999.3136. ISSN 0022-2836.
- ^ Pellegrini, Marco (2015). "Tandem Repeats in Proteins: Prediction Algorithms and Biological Role". Frontiers in Bioengineering and Biotechnology. 3. doi:10.3389/fbioe.2015.00143. ISSN 2296-4185. PMC 4585158. PMID 26442257.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link) - ^ Tompa, Peter (2003-08-18). "Intrinsically unstructured proteins evolve by repeat expansion". BioEssays. 25 (9): 847–855. doi:10.1002/bies.10324. ISSN 0265-9247.
- ^ Simon, Michelle; Hancock, John M (2009). "Tandem and cryptic amino acid repeats accumulate in disordered regions of proteins". Genome Biology. 10 (6): R59. doi:10.1186/gb-2009-10-6-r59. ISSN 1465-6906.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Jorda, Julien; Xue, Bin; Uversky, Vladimir N.; Kajava, Andrey V. (2010-05-18). "Protein tandem repeats - the more perfect, the less structured". FEBS Journal. 277 (12): 2673–2682. doi:10.1111/j.1742-4658.2010.07684.x. ISSN 1742-464X.
- ^ a b Kajava, Andrey V. (2012). "Tandem repeats in proteins: From sequence to structure". Journal of Structural Biology. 179 (3): 279–288. doi:10.1016/j.jsb.2011.08.009. ISSN 1047-8477.
- ^ Paladin, Lisanna; Hirsh, Layla; Piovesan, Damiano; Andrade-Navarro, Miguel A.; Kajava, Andrey V.; Tosatto, Silvio C.E. (2016-11-29). "RepeatsDB 2.0: improved annotation, classification, search and visualization of repeat protein structures". Nucleic Acids Research. 45 (D1): D308–D312. doi:10.1093/nar/gkw1136. ISSN 0305-1048. PMC 5210593. PMID 27899671.
{{cite journal}}: CS1 maint: PMC format (link)