Human alpha-galactosidase A: nucleotide sequence of a cDNA clone encoding the mature enzyme.

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Abstract
The complete nucleotide sequence has been determined for a .lambda.gt11 cDNA clone (.lambda.AG18) containing the full-length coding region for the mature lysosomal form of human .alpha.-galactosidase A (.alpha.-Gal A; EC 3.2.1.22). The .lambda.AG18 insert contained a 1226-base-pair sequence with an open reading frame encoding 398 amino acids of the mature polypeptide (predicted Mr = 45.356) and the last 5 amino acids of the propeptide sequence. The poly(A) signals AATACA and ATTAAA occurred 28 and 11 nucleotide prior to the TAA stop codon, respectively. There was no 3'' untranslated region as the poly(A) sequence immediately followed the TAA termination codon; a second independently cloned cDNA confirmed this finding. The predicted amino acid sequence was colinear with 86 nonoverlapping residues (22% of the mature subunit) determined by microsequencing amino-termial, tryptic, and cyanogen bromide peptides of the purified mature enzyme. Four potential N-glycosylation sites were identified, all of which occurred at predicted .beta. turns in hydrophilic regions of seconary structure. RNA transfer hybridization analysis of HeLa poly(A)+ RNA demonstrated a single 1.45-kolobase band whose signal was decreased by prior immunoabsorption of polysomes with monospecific .alpha.-Gal A antibodies. Searches of nuclei acid and protein data bases did not reveal significant homology even with the limited sequences available for mammalian lysosomal enzymes.