Human triosephosphate isomerase cDNA and protein structure. Studies of triosephosphate isomerase deficiency in man.

L E Maquat,R Chilcote,P M Ryan

doi:10.1016/s0021-9258(19)83687-6

Abstract

Nine cDNA clones of human adult liver triosephosphate (TP) isomerase have been isolated and characterized. All nine appear to be derived from a single mRNA species. DNA sequencing of one clone, designated pHTPI-5a, defined the last two nucleotides of the methionine initiation codon, the entire 744-nucleotide coding region of the mature polypeptide, and the entire 448-nucleotide 3' untranslated region. The frequency of TP isomerase clones in the cDNA library suggests that TP isomerase mRNA is present in adult liver at approximately 25 copies/cell. A single, low abundance TP isomerase mRNA species was detected in RNA isolated from normal human fibroblast cell lines. Analysis of TP isomerase mRNA levels in cultured fibroblasts of individuals that are homozygous for TP isomerase deficiency revealed normal levels in one and approximately 40% of normal levels in another. From this small patient sampling, it can be concluded that the genetic basis for TP isomerase deficiency is heterogeneous.

Highlights

From the $Department of Human Genetics, RoswellPark Memorial Institute, New York State Department of Health, Buffalo, New York 14263 and the §Department of Pediatrics, Wylers Children’sHospital, University of Chicago, Chicago, Illinois 60637
The frequency of TP isomerase clones in the cDNA library suggests that TP isomerase mRNA is present in adult liverat approximately 25 copies/cell
Triosephosphate Isomerase Sequences in Human, Mouse, cellulose (P-L Biochemicals) [30].Total or polyadenylated RNA was and Rabbit GenomicDNA-A short TP isomerasecDNA clone electrophoresed in a 1.2% agarose-2.2M formaldehydeslab gel, trans- has been identified by sequencing random clones of a rabbit ferred to nitrocellulose [31], and hybridized to a 32P-labeledsubclone of pHTPI-5a

Summary

Introduction

TP isomerase activity isreduced in all tissues andfluids that have been tured fibroblasts of individuals that are homozygous examined including erythrocytes, leukocytes, skeletal muscle, for TP isomerase deficiency revealednormal levels in spinal fluid, and platelets [17, 18].Recently, several groups one and approximately 40%of normal levels in an- have demonstrated thaatsignificant percentageof the human other. From this small patient sampling, it can be con- population carries a TP isomerase null allele (50% enzyme cluded that the genetic basis for TP isomerase defi- activity, 50% immunological cross-reactingmaterial).In a ciency is heterogeneous

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Results

Conclusion