OCCURRENCE OF POLY(ALPHA-2,8-DEAMINONEURAMINIC ACID) IN MAMMALIAN-TISSUES - WIDESPREAD AND DEVELOPMENTALLY-REGULATED BUT HIGHLY SELECTIVE EXPRESSION ON GLYCOPROTEINS

In tissues of higher organisms homopolymers of alpha 2,8-linked N-acet ylneuraminic acid can be found as a posttranslational modification on selected proteins, We report here the discovery of homopolymers of alp ha 2,8-linked deaminoneuraminic acid [poly(alpha 2,8-KDN)] in various tissues derived from all three germ layers in vertebrates including ma mmals, The monoclonal antibody kdn8kdn in conjunction with a bacterial KDNase permitted the detection of poly(alpha 2,8-KDN) by immunohistoc hemistry and immunoblotting. Further evidence for the existence of pol y(alpha 2,8-KDN) was obtained by gas/liquid chromatography. The poly(a lpha 2,8-KDN) glycan was detectable in all tissues studied with the ex ception of mucus-producing cells present in various organs, the extrac ellular matrix, and basement membranes, However, in certain organs suc h as muscle, kidney, lung, and brain its expression was developmentall y regulated, Despite its widespread tissue distribution, the poly(alph a 2,8-KDN) glycan was detected on a single 150-kDa glycoprotein except for a single >350-kDa glycoprotein in kidney, which makes it most dis tinctive among polysialic acids, The ubiquitous yet selective expressi on may be indicative of a general function of the poly(alpha 2,8-KDN)- bearing glycoproteins.