exonuclease 1 (hExo1, EXO1, EXOI, HEX1)

Function: 1) 5'->3' double-stranded DNA exonuclease 2) cryptic 3'->5' double-stranded DNA exonuclease activity (putative) 3) role in DNA mismatch repair to excise mismatch-containing DNA tracts directed by strand breaks located either 5' or 3' to the mismatch 3) endonuclease activity against 5' overhanging flap structures similar to those generated by displacement synthesis when DNA polymerase encounters the 5' end of a downstream Okazaki fragment 4) required for somatic hypermutation & class switch recombination of immunoglobulin genes 5) required for male & female meiosis 6) interacts with MLH1-PMS2 heterodimer via MLH1 7) interacts with MSH3 8) interacts with the MSH2-MSH6 heterodimer via MSH2 - interaction may increase processivity of 5'->3' exonuclease activity 9) interacts with PCNA - interaction may both stimulate cryptic 3'->5' exonuclease activity & suppress the 5'->3' exonuclease activity 10) interacts with WRN - interaction stimulates both the 5'->3' exonuclease activity & cleavage of 5' overhanging flap structures 11) interacts with RECQL/RECQ1 - interaction stimulates cleavage of 5' overhanging flap structures Structure: - belongs to the XPG/RAD2 endonuclease family, EXO1 subfamily Compartment: - nucleus - colocalizes with PCNA to discrete nuclear foci in S-phase Alternative splicing: named isoforms=2 Expression: - expressed in bone marrow, testis thymus > colon, lymph nodes, ovary, placenta, prostate, small intestine, spleen, stomach - expressed in fetal liver > fetal brain, heart, kidney, spleen & thymus Pathology: - germline deletions are not associated with clinically manifested colorectal tumors Polymorphism: - most naturally occurring variants are not associated with disposition to hereditary non-polyposis colorectal cancer (HNPCC)

General

exodeoxyribonuclease phosphoprotein

Properties

SIZE: MW = 94 kD entity length = 846 aa COMPARTMENT: cell nucleus MOTIF: N-domain {1-99} interaction with MSH3 {129-387} MOTIF: I-domain {138-229} interaction with MLH1 {388-490} Ser phosphorylation site {S598} interaction with MLH1 {787-846}

Database Correlations

OMIM 606063 UniProt Q9UQ84 PFAM correlations

References

UniProt :accession Q9UQ84