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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot Q96Q11: Variant p.Ile326Thr

CCA tRNA nucleotidyltransferase 1, mitochondrial
Gene: TRNT1
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Variant information Variant position: help 326 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Type of variant: help LP/P [Disclaimer] The variants are classified into three categories: LP/P, LB/B and US.
  • LP/P: likely pathogenic or pathogenic.
  • LB/B: likely benign or benign.
  • US: uncertain significance
Residue change: help From Isoleucine (I) to Threonine (T) at position 326 (I326T, p.Ile326Thr). Indicates the amino acid change of the variant. The one-letter and three-letter codes for amino acids used in UniProtKB/Swiss-Prot are those adopted by the commission on Biochemical Nomenclature of the IUPAC-IUB.
Physico-chemical properties: help Change from medium size and hydrophobic (I) to medium size and polar (T) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help -1 The score within a Blosum matrix for the corresponding wild-type to variant amino acid change. The log-odds score measures the logarithm for the ratio of the likelihood of two amino acids appearing by chance. The Blosum62 substitution matrix is used. This substitution matrix contains scores for all possible exchanges of one amino acid with another:
  • Lowest score: -4 (low probability of substitution).
  • Highest score: 11 (high probability of substitution).
More information can be found on the following page
Variant description: help In SIFD; decreased CCA tRNA nucleotidyltransferase activity; abolished homodimerization and disulfide bond formation. Any additional useful information about the variant.


Sequence information Variant position: help 326 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 434 The length of the canonical sequence.
Location on the sequence: help VTKLDLRLKIAKEEKNLGLF I VKNRKDLIKATDSSDPLKPY The residue change on the sequence. Unless the variant is located at the beginning or at the end of the protein sequence, both residues upstream (20) and downstream (20) of the variant will be shown.
Residue conservation: help The multiple alignment of the region surrounding the variant against various orthologous sequences. 
Human                         VTKLDLRLKIAKEEKNLGLFIVKNRKDLIKATDSSDPLKPY

Mouse                         VTKLDLRLKISKEEKNLGLFIVKNRKDLIKATDSSEPLKPY

Zebrafish                     VENLDQRLKVSREEKNLGLFLVKYRRDLVKGHDEHDTMKPY
Sequence annotation in neighborhood: help The regions or sites of interest surrounding the variant. In general the features listed are posttranslational modifications, binding sites, enzyme active sites, local secondary structure or other characteristics reported in the cited references. The "Sequence annotation in neighborhood" lines have a fixed format:
  • Type: the type of sequence feature.
  • Positions: endpoints of the sequence feature.
  • Description: contains additional information about the feature.
TypePositionsDescription
Chain 42 – 434 CCA tRNA nucleotidyltransferase 1, mitochondrial
Alternative sequence 58 – 434 Missing. In isoform 3.
Mutagenesis 326 – 326 I -> A. Decreased CCA tRNA nucleotidyltransferase activity; abolished homodimerization and disulfide bond formation.
Helix 317 – 329



Literature citations
Mutations in TRNT1 cause congenital sideroblastic anemia with immunodeficiency, fevers, and developmental delay (SIFD).
Chakraborty P.K.; Schmitz-Abe K.; Kennedy E.K.; Mamady H.; Naas T.; Durie D.; Campagna D.R.; Lau A.; Sendamarai A.K.; Wiseman D.H.; May A.; Jolles S.; Connor P.; Powell C.; Heeney M.M.; Giardina P.J.; Klaassen R.J.; Kannengiesser C.; Thuret I.; Thompson A.A.; Marques L.; Hughes S.; Bonney D.K.; Bottomley S.S.; Wynn R.F.; Laxer R.M.; Minniti C.P.; Moppett J.; Bordon V.; Geraghty M.; Joyce P.B.; Markianos K.; Rudner A.D.; Holcik M.; Fleming M.D.;
Blood 124:2867-2871(2014)
Cited for: INVOLVEMENT IN SIFD; VARIANTS SIFD ILE-154; VAL-158; SER-166; ILE-190; THR-223; THR-326 AND GLU-416; CHARACTERIZATION OF VARIANTS SIFD ILE-154; VAL-158; SER-166; ILE-190; THR-223 AND THR-326; FUNCTION; CATALYTIC ACTIVITY; Analysis of the pathogenic I326T variant of human tRNA nucleotidyltransferase reveals reduced catalytic activity and thermal stability in vitro linked to a conformational change.
Leibovitch M.; Reid N.E.; Victoria J.; Hanic-Joyce P.J.; Joyce P.B.M.;
Biochim. Biophys. Acta 1867:616-626(2019)
Cited for: VARIANT SIFD THR-326; CHARACTERIZATION OF VARIANT SIFD THR-326; FUNCTION; CATALYTIC ACTIVITY; SUBUNIT; DISULFIDE BOND; MUTAGENESIS OF ILE-326 AND CYS-373;
Disclaimer: Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. They are not in any way intended to be used as a substitute for professional medical advice, diagnostic, treatment or care.