Abstract
Complementary DNA clones of prolidase (imidodipeptidase, EC 3.4.13.9) were isolated from human liver and placental cDNA libraries. Two clones named lambda PL21 and lambda PP6 from the liver and placental cDNA libraries, respectively, were analyzed in detail. The first clone, lambda PL21, carried a cDNA insert of 1.7 kilobase pairs and covered all the coding region of human prolidase mRNA. The second clone, lambda PP6, contained a 1.8-kilobase insert with a full-length 3'-untranslated region. Comparison of the amino acid sequence predicted from the nucleotide sequence of the cDNA insert of the two clones with the partial amino acid sequence determined by Edman degradation of peptides derived from human erythrocyte prolidase established that both clones code for human prolidase. The amino terminus of the human mature enzyme is blocked and seems to begin with the sequence X-Ala-Ala-Ala. Presumably no processing occurs at the carboxyl terminus. The mature enzyme is composed of 492 residues, corresponding to Mr 54,305. The sequence of prolidase is unique and not similar to any known protein, except for a significant similarity to regions of F1-ATPase alpha and beta subunits from various sources. The gene has been mapped to the short arm of chromosome 19 (19p13.2). Elucidation of the complete amino acid sequence and the gene location of prolidase should provide the basis for understanding structure-function relationships and also inherited disorders caused by deficiency of this metabolically important enzyme.
Highlights
From the $Department of Pediatrics, Kumnmoto University Medical SchoolK, umamoto 860, the §Department of Pediatrics, School of Medicine, Tohoku University,Sendai 980, and the llhboratory of Biomedical Polymer Science, Schoolof Medicine, Fujita-Gakuen Health University, Toyoake, Aichi 470-1I, Japan
Comparison of the amino acid sequence predicted from the nucleotide sequence of the cDNA insert of the twoclones with the partiaal mino acid sequence determined by Edman degradation of peptides derived from human erythrocyteprolidase established that both clones code for human prolidase
Polymorphisms of prolidase have been studied by gel electrophoresis [5], and a tight linkage of the polymorphisms and themyotonic dystrophy trait has been demonstrated ( 6 )
Summary
Fumio Endo/, Akito Tanouel, Hiroshi NakaiB, Akira HataS, Yasuhiro Indo/, Koiti Titaniq, and Ichiro MatsudaS. To better comprehend structure-function relationships, Elucidation of the complete amino acid sequence and the gene location of prolidase should provide the basis four nderstandingstructure-functionrelationships and inherited disorders caused by deficiency of this metabolically important enzyme. Prolidase (peptidase D, imidodipeptidase, EC 3.4.13.9) is a ubiquitous enzyme which splits dipeptides with a prolyl residue in the carboxyl-terminal position Deficiency of this enzyme results in a syndrome with abnormalities of skin and other collagenous tissues [1].The affected subjects excrete massive amounts of iminopeptides in the urine ( l ) , and these peptides function as thesubstrate for prolidase [2]. One plaque (XPL1) reactive with the antibody was purified through four successive rounds of screening
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