CDNA AND GENOMIC CLONING OF HUMAN PALMITOYL-PROTEIN THIOESTERASE (PPT), THE ENZYME DEFECTIVE IN INFANTILE NEURONAL CEROID-LIPOFUSCINOSIS

Palmitoyl-protein thioesterase (PPT) is a small glycoprotein that remo ves palmitate groups from cysteine residues in lipid-modified proteins . We recently reported mutations in PPT in patients with infantile neu ronal ceroid lipofuscinosis (INCL), a severe neurodegenerative disorde r (J. Vesa et al., 1995, Nature 376: 584-587). INCL is characterized b y the accumulation of proteolipid storage material in brain and other tissues, suggesting that the disease is a consequence of abnormal cata bolism of acylated proteins. In the current paper, we report the seque nce of the human PPT cDNA and the structure of the human PPT gene. The cDNA predicts a protein of 306 amino acids that contains a 25-amino-a cid signal peptide, three N-linked glycosylation sites, and consensus motifs characteristic of thioesterases. Northern analysis of a human t issue blot revealed ubiquitous expression of a single 2.5-kb mRNA, wit h highest expression in lung, brain, and heart. The human PPT gene spa ns 25 kb and is composed of seven coding exons and a large eighth exon , containing the entire 3'-untranslated region of 1388 bp. An Alu repe at and promoter elements corresponding to putative binding sites for s everal general transcription factors were identified in the 1060 nucle otides upstream of the transcription start site, The human PPT cDNA se quence and gene structure will provide the means for the identificatio n of further causative mutations in INCL and facilitate genetic screen ing in selected high-risk populations. (C) 1996 Academic Press, Inc.