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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P50336: Variant p.Pro256Arg

Protoporphyrinogen oxidase
Gene: PPOX
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Variant information Variant position: help 256 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Type of variant: help US 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 Proline (P) to Arginine (R) at position 256 (P256R, p.Pro256Arg). 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 (P) to large size and basic (R) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help -2 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 Found in patients with the homozygous variant of variegate porphyria; uncertain significance; results in reduction of activity in a prokariotyc expression system but has normal activity when expressed in an eukaryotic system. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 256 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 477 The length of the canonical sequence.
Location on the sequence: help LPQALETHLTSRGVSVLRGQ P VCGLSLQAEGRWKVSLRDSS 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                         LPQALETHLTS-RGVSVLRGQPVCGLSLQAEGR-W---KVSLRDSS

Mouse                         LPQALHNHLAS-KGVTVLSGQPVCGLSLQPEGR-W---KVS

Bovine                        LPQALHAHLTS-RGVSVLQGQPVCGLSLQAEGR-W---KVS

Slime mold                    MIQKLKSLIESDSLTKLYLSTSIVEIEKDVTNGTLK-VTDN

Baker's yeast                 FPKIVRNALNEFKNVKIVTGNPVTQIMKRPANETTIGLKAK

Fission yeast                 ITLSIADELKKMPNVKIHLNKPAK----------T---LVP

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 1 – 477 Protoporphyrinogen oxidase
Binding site 257 – 257



Literature citations
Variegate porphyria in Western Europe: identification of PPOX gene mutations in 104 families, extent of allelic heterogeneity, and absence of correlation between phenotype and type of mutation.
Whatley S.D.; Puy H.; Morgan R.R.; Robreau A.M.; Roberts A.G.; Nordmann Y.; Elder G.H.; Deybach J.C.;
Am. J. Hum. Genet. 65:984-994(1999)
Cited for: VARIANTS ARG-256 AND HIS-304; VARIANTS VP PRO-38; GLU-40; PRO-73; GLY-84; PRO-85; VAL-143; CYS-152; PRO-154; MET-158; HIS-168; VAL-172; ARG-232; HIS-281 DEL; ASP-282; PRO-295; GLY-335; PRO-350; PRO-444; ARG-453 AND VAL-453; Homozygous variegate porphyria: 20 y follow-up and characterization of molecular defect.
Kauppinen R.; Timonen K.; von und zu Fraunberg M.; Laitinen E.; Ahola H.; Tenhunen R.; Taketani S.; Mustajoki P.;
J. Invest. Dermatol. 116:610-613(2001)
Cited for: VARIANT VP THR-12; VARIANT ARG-256; CHARACTERIZATION OF VARIANT VP THR-12; CHARACTERIZATION OF VARIANT ARG-256;
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.