Human
alpha-L-fucosidase, a lysosomal
enzyme, hydrolyzes alpha-L-
fucose from
glycolipids and
glycoproteins. Its activity is deficient in human
fucosidosis an autosomal recessive disease. In order to understand the molecular basis of this lysosomal storage disorder we have cloned several cDNAs coding for human
alpha-L-fucosidase from a human
hepatoma and a human liver cDNA library constructed in lambda gt11. Compiling the
cDNA sequences of these clones we have identified 1,829 base pairs (bp) encoding human
alpha-L-fucosidase. This includes an open reading frame of 1,172 bp, a consensus polyadenylation signal AAT AAA and a
poly(A)+ tail. The sequence is incomplete at the 5'-end, and clones encoding the amino terminus of the native
protein, the propeptide and leader signal have not yet been isolated. The open reading frame encodes for 390
amino acids with a calculated Mr of 45,557. This represents 78-95% of the mature processed
alpha-L-fucosidase. The availability of these
cDNA clones has enabled us to map the structural gene for
alpha-L-fucosidase to chromosome 1p34.1-1p36.1 by Southern blot analysis of
DNA from human-rodent somatic cell hybrids and by in situ hybridization. Furthermore, a Pvu II restriction fragment length polymorphism (RFLP) has been identified at the human
alpha-L-fucosidase gene locus. Analysis of
mRNA by Northern blotting gives a major species of 2.25 kb. In 4 patients with
fucosidosis no
mRNA signal was detected and Western blots gave no immunoreactive
enzyme. Southern blotting after
Eco RI digestion in two
fucosidosis families revealed a banding abnormality (extra 6-kb band).(ABSTRACT TRUNCATED AT 250 WORDS)