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RNA polymerase II subunit A C-terminal domain phosphatase SSU72
Known also as: CTD phosphatase SSU72
Known abbreviations: SSU72, HSPC182, PNAS-120
Yeast homolog: not known
Protein
Structures Models Domains Secondary structure Disorder |
Top 3 models:
 |  |  |
| Template: 3o2q, chain B Method: hhsearch Fragment: 1-194 | Template: 3p9y, chain A Method: hhsearch Fragment: 1-194 | Template: 4h3k, chain B Method: blastp Fragment: 1-194 |
This protein has alternative isoforms:
Isoform 1:
| Sequence length: | 194 aa |
| Molecular weight: | 22.575 kDa |
| Isoelectric point: | 5.08 |
1........10........20........30........40........50........60........70........80........90........100.......110.......120.......130
MPSSPLRVAVVCSSNQNRSMEAHNILSKRGFSVRSFGTGTHVKLPGPAPDKPNVYDFKTTYDQMYNDLLRKDKELYTQNGILHMLDRNKRIKPRPERFQNCKDLFDLILTCEERVYDQVVEDLNSREQET
CQPVHVVNVDIQDNHEEATLGAFLICELCQCIQHTEDMENEIDELLQEFEEKSGRTFLHTVCFY
Isoform 2:
| Sequence length: | 153 aa |
| Molecular weight: | 16.931 kDa |
| Isoelectric point: | 9.7 |
1........10........20........30........40........50........60........70........80........90........100.......110.......120.......130
MPSSPLRVAVVCSSNQNRSMEAHNILSKRGFSVRSFGTGTHVKLPGPAPDKPNVYDFKTTYDQMYNDLLRKDKELYPSGLPFKNPPCGPPWKVLRVARAQEACHPVQCTHWLLCLCESLVSIPGARRIVH
GLVPVPPMAVGVVRRTDTVWGSP
Enzyme
EC number: 3.1.3.16
Name: Phosphoprotein phosphatase
Reaction: A phosphoprotein + H(2)O <=> a protein + phosphate
Gene location: 1p36.33
Summary
SSU72 is involved in the C-terminal domain of RNA polymerase II dephosphorylation, RNA processing and termination.
Ssu72p was originally identified by its genetic interaction with the transcription factor TFIIB, as a mutation in Ssu72p disrupted this interaction and affected the accuracy of start site selection.
It is essential for the cleavage reaction but is not required for polyadenylation. Ssu72p interacts with Pta1p, Cft2p/Ydh1p and the Rpb2p subunit of PolII.
Upon binding to Pta1p, Ssu72p functions as a phosphatase with specificity for the fifth serine of the heptapeptide repeat in the CTD of PolII.
In human Ssu72 has been identified as an interacting protein of the retinoblastoma tumor suppressor, Rb. Similar to its yeast homolog, hSsu72 binds directly to TFIIB and Pta1p and exhibits phosphatase activity, but its role in 3?-end processing is still unknown. hSsu72 cannot rescue a lethal mutation in Ssu72 in yeast [225]. human and yeast homologs shares 72% sequence identity.
Interacts with RB1.
Interacts with GTF2B and CD226.
See this protein in other databases:
Literature:
- St-Pierre B, Liu X, Kha LC et al. Conserved and specific functions of mammalian ssu72. Nucleic Acids Res 2005 33(2):464-77, doi: 10.1093/nar/gki171, PMID: 15659578.
- Ansari A, Hampsey M. A role for the CPF 3"-end processing machinery in RNAP II-dependent gene looping. Genes Dev 2005 19(24):2969-78, doi: 10.1101/gad.1362305, PMID: 16319194.
- Zhang Y, Zhang M, Zhang Y et al. Crystal structure of Ssu72, an essential eukaryotic phosphatase specific for the C-terminal domain of RNA polymerase II, in complex with a transition state analogue. Biochem J 2011 434(3):435-44, doi: 10.1042/BJ20101471, PMID: 21204787.
- Zhang DW, Mosley AL, Ramisetty SR et al. Ssu72 phosphatase-dependent erasure of phospho-Ser7 marks on the RNA polymerase II C-terminal domain is essential for viability and transcription termination. J Biol Chem 2012 287(11):8541-51, doi: 10.1074/jbc.M111.335687, PMID: 22235117.
- Xiang K, Manley JL, Tong L et al. An unexpected binding mode for a Pol II CTD peptide phosphorylated at Ser7 in the active site of the CTD phosphatase Ssu72. Genes Dev 2012 26(20): 2265-70, doi: 10.1101/gad.198853.112, PMID: 23070812.
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