Department of Medical Biochemistry, Institute of Medical Biology, University of Tromsø, Norway. hildefr@fagmed.uit.no
Lysosomal alpha-mannosidase (LAMAN) (EC 3.2.1.24) is an exoglycosidase involved in the ordered degradation of N-linked oligosaccharides. Lack of LAMAN activity leads to the lysosomal storage disorder alpha-mannosidosis (MIM No. 248500). We determined the genomic organization of the human lysosomal alpha-mannosidase gene (laman; HGMW-approved symbol MANB) by using oligonucleotide primers designed from the human laman cDNA sequence as part of a PCR-based strategy. The gene spanned 21.5 kb and contained 24 exons. By primer extension analysis, the major transcription initiation sites were mapped to positions -309, -196, and -191 relative to the first in-frame ATG. No CAAT or TATA sequences could be identified within 134 bp upstream of the transcription initiation sites, but the 5' flanking region contained several GC-rich regions with putative binding sites for the transcription factors SP-1, AP-2, and ETF.