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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P21912: Variant p.Leu257Val

Succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial
Gene: SDHB
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Variant information Variant position: help 257 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 Leucine (L) to Valine (V) at position 257 (L257V, p.Leu257Val). 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 Similar physico-chemical property. Both residues are medium size and hydrophobic. 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 MC2DN4; decreased succinate dehydrogenase (ubiquinone) activity; decreased protein levels in homozygous patient cells. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 257 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 280 The length of the canonical sequence.
Location on the sequence: help PFSLYRCHTIMNCTRTCPKG L NPGKAIAEIKKMMATYKEKK 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                         PFSLYRCHTIMNCTRTCPKGLNPGKAIAEIKKMMATYKEKK

Mouse                         PFSVYRCHTIMNCTQTCPKGLNPGKAIAEIKKMMATYKEKR

Rat                           PFSLYRCHTIMNCTQTCPKGLNPGKAIAEIKKMMATYKEKR

Pig                           PFSLYRCHTIMNCTGTCPKGLNPGKAIAEIKKMMATYKEKK

Bovine                        PFSLYRCHTIMNCTQTCPKGLNPGKAIAEIKKMMATYKEKQ

Chicken                       PFSLYRCHTIMNCTRTCPKGLNPGKAIAEIKKMMATYKEKA

Xenopus laevis                PFSLYRCHTIMNCTRTCPKGLNPGKAIAEIKKMMAMYKERA

Xenopus tropicalis            PFSLYRCHTIMNCTRTCPKGLNPGKAIAEIKKMMATYKERA

Zebrafish                     PFSLYRCHTIMNCTRTCPKGLNPGKAIAEIKKMMVTYKQKD

Caenorhabditis elegans        SFSAFKCHTIMNCTKTCPKHLNPAKAIGEIKSLLTGFTSKP

Drosophila                    PFSVYRCHTIMNCTRTCPKGLNPGRAIAEIKKLLSGLASKP

Slime mold                    QMKVYKCHTIMNCTAVCPKGLNPGKSIANIKYLLAHN----

Baker's yeast                 SMSLYRCHTIMNCTRTCPKGLNPGLAIAEIKKSLAFA----

Fission yeast                 SMSVYRCHTIMNCARTCPKGLNPGLAIAKVKALMATA----
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 29 – 280 Succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial
Binding site 243 – 243
Binding site 249 – 249
Binding site 253 – 253



Literature citations
Leukoencephalopathy due to Complex II Deficiency and Bi-Allelic SDHB Mutations: Further Cases and Implications for Genetic Counselling.
Groenborg S.; Darin N.; Miranda M.J.; Damgaard B.; Cayuela J.A.; Oldfors A.; Kollberg G.; Hansen T.V.O.; Ravn K.; Wibrand F.; Oestergaard E.;
JIMD Rep. 33:69-77(2017)
Cited for: VARIANTS MC2DN4 VAL-48; HIS-230 AND VAL-257; CHARACTERIZATION OF VARIANT MC2DN4 VAL-257; FUNCTION; CATALYTIC ACTIVITY; ALTERNATIVE SPLICING;
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.