Symplekin

Known abbreviations: Symplekin, SPK, SYM, SYMPK

Yeast homolog: PTA1

Protein

1274

DUF3453

Symplekin_C

Structures

Models
Domains

Secondary structure

NTD, CTD

Top 3 models:


Template: 3o2t, chain A Method: hhsearch Fragment: 3-395	Template: 3gs3, chain A Method: hhsearch Fragment: 14-288	Template: 2po4, chain A Method: compass Fragment: 92-817

This protein has alternative isoforms:
Isoform 1:

Sequence length:	1274 aa
Molecular weight:	141.148 kDa
Isoelectric point:	5.88

Sequence:
1........10........20........30........40........50........60........70........80........90........100.......110.......120.......130
MASGSGDSVTRRSVASQFFTQEEGPGIDGMTTSERVVDLLNQAALITNDSKITVLKQVQELIINKDPTLLDNFLDEIIAFQADKSIEVRKFVIGFIEEACKRDIELLLKLIANLNMLLRDENVNVVKKAI
LTMTQLYKVALQWMVKSRVISELQEACWDMVSAMAGDIILLLDSDNDGIRTHAIKFVEGLIVTLSPRMADSEIPRRQEHDISLDRIPRDHPYIQYNVLWEEGKAALEQLLKFMVHPAISSINLTTALGSL
ANIARQRPMFMSEVIQAYETLHANLPPTLAKSQVSSVRKNLKLHLLSVLKHPASLEFQAQITTLLVDLGTPQAEIARNMPSSKDTRKRPRDDSDSTLKKMKLEPNLGEDDEDKDLEPGPSGTSKASAQIS
GQSDTDITAEFLQPLLTPDNVANLVLISMVYLPEAMPASFQAIYTPVESAGTEAQIKHLARLMATQMTAAGLGPGVEQTKQCKEEPKEEKVVKTESVLIKRRLSAQGQAISVVGSLSSMSPLEEEAPQAK
RRPEPIIPVTQPRLAGAGGRKKIFRLSDVLKPLTDAQVEAMKLGAVKRILRAEKAVACSGAAQVRIKILASLVTQFNSGLKAEVLSFILEDVRARLDLAFAWLYQEYNAYLAAGASGSLDKYEDCLIRLL
SGLQEKPDQKDGIFTKVVLEAPLITESALEVVRKYCEDESRTYLGMSTLRDLIFKRPSRQFQYLHVLLDLSSHEKDKVRSQALLFIKRMYEKEQLREYVEKFALNYLQLLVHPNPPSVLFGADKDTEVAA
PWTEETVKQCLYLYLALLPQNHKLIHELAAVYTEAIADIKRTVLRVIEQPIRGMGMNSPELLLLVENCPKGAETLVTRCLHSLTDKVPPSPELVKRVRDLYHKRLPDVRFLIPVLNGLEKKEVIQALPKL
IKLNPIVVKEVFNRLLGTQHGEGNSALSPLNPGELLIALHNIDSVKCDMKSIIKATNLCFAERNVYTSEVLAVVMQQLMEQSPLPMLLMRTVIQSLTMYPRLGGFVMNILSRLIMKQVWKYPKVWEGFIK
CCQRTKPQSFQVILQLPPQQLGAVFDKCPELREPLLAHVRSFTPHQQAHIPNSIMTILEASGKQEPEAKEAPAGPLEEDDLEPLTLAPAPAPRPPQDLIGLRLAQEKALKRQLEEEQKLKPGGVGAPSSS
SPSPSPSARPGPPPSEEAMDFREEGPECETPGIFISMDDDSGLTEAALLDSSLEGPLPKETAAGGLTLKEERSPQTLAPVGEDAMKTPSPAAEDAREPEAKGNS

Isoform 2:

Sequence length:	673 aa
Molecular weight:	74.523 kDa
Isoelectric point:	7.3

Summary
Symplekin is a nuclear protein that functions in the regulation of polyadenylation and promotes gene expression. It is thought to serve as a scaffold for recruiting regulatory factors to the polyadenylation complex. It also participates in 3'-end maturation of histone mRNAs, which do not undergo polyadenylation. The protein also localizes to the cytoplasmic plaques of tight junctions in some cell types.

Two separate isoforms are known. The first 964 residues of the two forms of symplekin are identical, suggesting that they are derived from alternative splicing. Symplekin and Pta1p share very weak sequence homology, but a putative conserved region between the two proteins have been identified by sequence analysis, with 17% identity and 31% similarity.

May have a house-keeping rule.

Found in a heat-sensitive complex at least composed of several cleavage and polyadenylation specific and cleavage stimulation factors.

Interacts with CPSF2, CPSF3 and CSTF2.
Interacts with HSF1 in heat-stressed cells.

It is detected in testis, expressed in polar epithelia and Sertoli cells but not in vascular endothelia. Additionally, the protein is detected in stomach, duodenum, pancreas, liver, fetal brain, carcinomas, lens-forming cells, fibroblasts, lymphocytes, lymphoma cells, erythroleukemia cells but not in endothelium of vessels, epidermis, intercalated disks, Purkinje fiber cells of the heart and lymph node.

Could be used as a differentiation marker in the differential diagnosis of tumors.

See this protein in other databases:

Literature:

Kolev NG, Steitz JA. Symplekin and multiple other polyadenylation factors participate in 3"-end maturation of histone mRNAs. Genes Dev 2005 19(21):2583-92, doi: 10.1101/gad.1371105, PMID: 16230528.
Sullivan KD, Steiniger M, Marzluff WF et al. A core complex of CPSF73, CPSF100, and Symplekin may form two different cleavage factors for processing of poly(A) and histone mRNAs. Mol Cell 2009 34(3):322-32, doi: 10.1016/j.molcel.2009.04.024, PMID: 19450530.
Kennedy SA, Frazier ML, Steiniger M et al. Crystal structure of the HEAT domain from the Pre-mRNA processing factor Symplekin. J Mol Biol 2009 392(1):115-28, doi: 10.1016/j.jmb.2009.06.062, PMID: 19576221.
Xiang K, Nagaike T, Xiang S et al. Crystal structure of the human symplekin-Ssu72-CTD phosphopeptide complex. Nature 2010 467(7316):729-33, doi: 10.1038/nature09391, PMID: 20861839.
Ruepp MD, Schweingruber C, Kleinschmidt N et al. Interactions of CstF-64, CstF-77, and symplekin: implications on localisation and function. Mol Biol Cell 2011 22(1):91-104, doi: 10.1091/mbc.E10-06-0543, PMID: 21119002.
Keon BH, Schafer S, Kuhn C et al. Symplekin, a novel type of tight junction plaque protein. J Cell Biol 1996 134(4):1003-18, doi: , PMID: 8769423.
Ueki K, Ramaswamy S, Billings SJ et al. Chromosomal localization to 19q13.3, partial genomic structure and 5" cDNA sequence of the human symplekin gene. Somat Cell Mol Genet 1997 23(3):229-31, doi: , PMID: 9330635.

Additional computationally mapped references ...

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