>gnl|CDD|144991 pfam01612, 3_5_exonuc, 3'-5' exonuclease. This domain is responsible for the 3'-5' exonuclease proofreading activity of E. coli DNA polymerase I (polI) and other enzymes, it catalyses the hydrolysis of unpaired or mismatched nucleotides. This domain consists of the amino-terminal half of the Klenow fragment in E. coli polI it is also found in the Werner syndrome helicase (WRN), focus forming activity 1 protein (FFA-1) and ribonuclease D (RNase D). Werner syndrome is a human genetic disorder causing premature aging; the WRN protein has helicase activity in the 3'-5' direction. The FFA-1 protein is required for formation of a replication foci and also has helicase activity; it is a homologue of the WRN protein. RNase D is a 3'-5' exonuclease involved in tRNA processing. Also found in this family is the autoantigen PM/Scl thought to be involved in polymyositis-scleroderma overlap syndrome. Length = 172

 Score = 67.7 bits (166), Expect = 2e-11
 Identities = 36/114 (31%), Positives = 62/114 (54%), Gaps = 7/114 (6%)

Query: 450 LSYLKKFFENEHFLKIGHNIKYDKLVLHR-YGISMRGFEDIMLMSYVLDSGRSSHDIASI 508
           L  LK+  E+ +  K+GHN K+D  VL R +GI +    D ML +Y+L   R SH +  +
Sbjct: 64  LEGLKRLLEDPNITKVGHNAKFDLEVLARDFGIKLENLFDTMLAAYLLGYPR-SHSLDDL 122

Query: 509 AQKWLSY-TRKEILKSRKSSIPIDKISDSQVQEHAIENSNVILQLWLLLRPKLI 561
           A+K+L     K    +         +S+ Q++ +A E+++ +L+L+  LR +L 
Sbjct: 123 AEKYLGVELDKSEQCADWR---ARPLSEEQLR-YAAEDADYLLRLYDKLRKELE 172