Complementary DNA cloning and characterization of RANDAM-2, a type I membrane molecule specifically expressed on glutamatergic neuronal cells in the mouse cerebrum

A membrane‐surface glycoprotein, RANDAM‐2, is one of the neuronal cell lineage‐specific antigens involved in the neuronal differentiation of P19 embryonic carcinoma (EC) cells and the mouse central nervous system (CNS). Complementary DNA cloning of RANDAM‐2 indicated that its nucleotide sequence completely matched that of PA2.26 antigen, a sialomucin‐like transmembrane glycoprotein previously found on tumorigenic keratinocytes. RANDAM‐2 transcripts were detectable from the embryonic stage of 6.5 days, and then the expression continued throughout the remaining embryonic stages and adulthood, with a localization restricted to the CNS. In growth factor‐induced neurospheres and adult cerebrum, RANDAM‐2‐expressing cells coincided well not only with nestin‐positive cells but also with glutamate‐positive neurons, but not with γ‐aminobutyric acid‐positive ones. These results indicate that RANDAM‐2 is one of the type I membrane surface antigens constitutively expressed on undifferentiated neuronal cells and the glutamatergic neuronal cells during mouse neurogenesis. © 2003 Wiley‐Liss, Inc.