nuclear autoantigen Sp-100; nuclear dot-associated Sp100 protein; speckled 100 kDa; Lysp100b (SP100)

Function: - may play a role in the control of gene expression - phosphorylated - sumoylated; sumoylation depends on a functional nuclear localization signal but is not necessary for nuclear import or nuclear body targeting - homodimer - splice variants heterodimerize - interacts with members of the HP1 family of nonhistone chromosomal proteins, such as CBX5 & CBX3 via the PxVxL motif - interacts with Epstein-Barr virus EBNA-LP Structure: - the HSR domain is important for the nuclear body targeting as well as for the dimerization - contains one Pro-Xaa-Val-Xaa-Leu (PxVxL) motif, which is required for interaction with chromoshadow domains; this motif requires additional residues -7, -6, +4 & +5 of the central Val which contact the chromoshadow domain - contains 2 HMG box DNA-binding domains - contains 1 HSR domain - contains 1 SAND domain Compartment: - nucleus - found in the nuclear body - subnuclear localization may be modulated by a) interferon b) cell cycle Alternative splicing: named isoforms=5 Expression: - widely expressed - Sp100-B is expressed only in spleen, tonsil, thymus, mature B-cell line & some T-cell line, but not in brain, liver, muscle or non-lymphoid cell lines - induced by interferon Pathology: - this antigen is recognized by autoantibodies from patients with primary biliary cirrhosis (PBC) Laboratory: - SP100 antibody in serum - SP100 IgG in serum Notes: - the major isoform Sp100-A, has a calculated MW of 54 kD, but exhibits aberrant electrophoretic mobilities, with an apparent MW of 100 kD

General

antigen nuclear protein phosphoprotein

Properties

SIZE: entity length = 879 aa MW = 100 kD COMPARTMENT: cell nucleus MOTIF: glycine-rich region {3-6} Ser phosphorylation site {S18} HSR {33-149} glutamate-rich region {156-164} MOTIF: glutamate residue (SEVERAL) Ser phosphorylation site {S157} peptide motif {284-297} Ser phosphorylation site {S327} Ser phosphorylation site {S328} Ser phosphorylation site {S331} Ser phosphorylation site {S334} Thr phosphorylation site {T335} Ser phosphorylation site {S407} Ser phosphorylation site {S409} Ser phosphorylation site {S410} Ser phosphorylation site {S451} Ser phosphorylation site {S452} Ser phosphorylation site {S453} Ser phosphorylation site {S456} Ser phosphorylation site {S459} nuclear translocation signal {536-553} nuclear translocation signal {568-592} SAND {595-676} HMG box SITE: 677-753 MOTIF: nuclear translocation signal {717-734} lysine-rich region {759-764} MOTIF: lysine residue (SEVERAL) HMG box SITE: 769-837 lysine-rich region {854-859} MOTIF: lysine residue (SEVERAL) glutamate-rich region {860-868} MOTIF: glutamate residue (SEVERAL)

Database Correlations

OMIM 604585 UniProt P23497 PFAM correlations Entrez Gene 6672 Kegg hsa:6672

References

UniProt :accession P23497