Nicotinamide Nucleotide Adenylyltransferase 1 (NMNAT1)

NMNAT1 contains a conserved N-terminal adenylyltransferase motif, an N-terminal N-glycosylation site, and several potential transmembrane regions. Northern blot analysis detected 3.1- and 4.1-kb transcripts expressed at variable levels in all tissues examined. The 3.1-kb transcript was more abundant, and expression was highest in skeletal muscle, heart, liver, and kidney; thymus and spleen showed a weak signal. Expression was reduced in all tumor cell lines examined except in a lymphoma cell line and a chronic myelogenous leukemia cell line. Purified recombinant NMNAT1 migrated with an apparent molecular mass of 33 kD by SDS-PAGE. Gel filtration analysis detected active recombinant enzyme at an apparent molecular mass of 139 kD, suggesting that NMNAT1 forms a homotetramer.