Abstract
DNA clones encoding beta-galactoside alpha 2,3-sialyltransferase have been isolated from mouse brain cDNA libraries using sequence information obtained from the conserved amino acid sequence of the previously cloned enzymes. The cDNA sequence revealed an open reading frame coding for 337 amino acids, and the deduced amino acid sequence showed 80% identity with that of porcine submaxillary gland Gal beta 1,3GalNAc alpha 2,3-sialyltransferase. The primary structure of this enzyme suggested a putative domain structure, like that in other glycosyltransferases, consisting of a short NH2-terminal cytoplasmic domain, a signal-membrane anchor domain, a proteolytically sensitive stem region, and a large COOH-terminal active domain. The identity of this enzyme was confirmed by construction of a recombinant sialyltransferase in which the NH2-terminal part including the cytoplasmic tail, signal-anchor domain and stem region was replaced with an immuno-globulin signal sequence. The expression of this recombinant in COS-7 cells resulted in secretion of a catalytically active and soluble form of the enzyme into the medium. This enzyme exhibited the transferase activity toward only the disaccharide moiety of Gal beta 1,3GalNAc of glycoproteins and glycolipids, no significant activity being detected for the other substrates tested.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
