Glycobiology Advance Access originally published online on May 16, 2006
Glycobiology 2006 16(9):863-873; doi:10.1093/glycob/cwl002
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Molecular cloning and characterization of rat Pomt1 and Pomt2
2 Glycobiology Research Group, Tokyo Metropolitan Institute of Gerontology, Foundation for Research on Aging and Promotion of Human Welfare, 35–2 Sakaecho, Itabashi-ku, Tokyo 173–0015, Japan; 3 Department of Neurology, Kyorin University School of Medicine, Mitaka, Tokyo 181–8611, Japan; and 4 Department of Pharmacology, New York University Medical Center, New York, NY 10016
1 To whom correspondence should be addressed; e-mail: endo{at}tmig.or.jp
Received on April 3, 2006; revised on May 10, 2006; accepted on May 11, 2006
Mammalian O-mannosylation, although an uncommon type of protein modification, is essential for normal brain and muscle development. Defective O-mannosylation causes congenital muscular dystrophy with abnormal neuronal migration [Walker–Warburg syndrome (WWS)]. Here, we have identified and cloned rat Pomt1 and Pomt2, which are homologues of human POMT1 and POMT2, with identities of 86 and 90%, respectively, at the amino acid level. Coexpression of both genes was found to be necessary for enzymatic activity, as is the case with human POMT1 and POMT2. Northern blot and reverse transcriptase polymerase chain reaction (RT–PCR) analyses revealed that rat Pomt1 and Pomt2 are expressed in all tissues but most strongly in testis. In situ hybridization histochemistry of rat brain revealed that Pomt1 and Pomt2 mRNA are coexpressed in neurons (dentate gyrus and CA1-CA3 region of the hippocampus and cerebellar Purkinje cells). Two transcription-initiation sites were observed in rat Pomt2, resulting in two forms: a testis form and a somatic form. The two forms had equal protein O-mannosyltransferase activity when coexpressed with rat Pomt1. Coexpression studies also showed that the human and rat protein O-mannosyltransferases are interchangeable, providing further evidence for the closeness of their structures.
Key words: glycosylation / Pomt1 and Pomt2 / protein O-mannosyltransferase activity / rat
* These contributed equally to this work.
The nucleotide sequences reported in this article have been submitted to the DDBJ/GenBank/EBI Data Bank with accession numbers AF192388 for rat Pomt1 and AB246667 for rat Pomt2.
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