Identification of cDNA clones of the mouse neural cell adhesion molecule L1

Two cDNA clones of the neural cell adhesion molecule L1 (Mr 200,000) were isolated using lambda gt10 and lambda gt11 libraries constructed from postnatal day 8 mouse brain poly(A)+ RNA. Clone K21 was selected and identified using immunoaffinity purified polyclonal antibodies. It was then used to isolate a secondary clone (K21-1), which hybridized with an oligonucleotide probe synthesized by reverse translation of the aminoterminal sequence of the 80 kDa carboxyterminal proteolytic fragment of L1. Blot hybridization analysis indicated that L1 is encoded by a single gene and transcribed by a single 6 kb mRNA which is present only in cells or tissues known to express L1.