Plxnb1^tm1Matl

Targeted mutagenesis using a promoterless gene trap vector ("targeted trapping") was used to insert a 9.4-kb placental alkaline phosphatase (PLAP) secretory cassette into intron 21. This results in transcription of a fusion mRNA joining upstream exons of the endogenous gene to the elements of the cassette, comprising a splice acceptor and a transmembrane domain coding sequence followed by the betageo (lacZ/neomycin resistance fusion) cDNA, an internal ribosomal entry site (IRES), and the human PLAP sequence with a polyadenylation signal. Two proteins are translated from this bicistronic transcript: a PLXNB1/Betageo fusion protein that is sequestered in an intracellular compartment of the neuronal cell body; and PLAP, which is expressed on the axonal surface. (Roland Freidel, data submission). Western blot of E11.5 whole embryo lysates confirmed the absence of protein in homozygous mutants. (J:228347)