MOUSE CYTOCHROME B561 - CDNA CLONING AND EXPRESSION IN RAT-BRAIN, MOUSE EMBRYOS, AND HUMAN GLIOMA CELL-LINES

A cDNA encoding cytochrome b561 has been isolated from a mouse brain c DNA library, which predicts a protein of 250 amino acids with a deduce d M-r of 27,770. Northern blot analysis of different mouse and rat tis sues revealed one major mRNA of 3300 bp, which is abundantly distribut ed in a number of neuroendocrine tissues. In addition, cytochrome mRNA levels in rat brain sections showed the highest distribution of cytoc hrome b561 in the hypothalamus, hippocampus, thalamus, and striatum, w ith a moderate level in the cerebral cortex, and the lowest levels in the olfactory bulb and cerebellum. Because non-neuronal cells in the c entral nervous system contained peptidyl cy-amidating monooxygenase (P AM), to which cytochrome b561 donates its electrons, we used RT-PCR to document the coexpression of cytochrome b561 with PAM and dopamine P- hydroxylase (DBH) in glioblastoma cells. Cytochrome b561 expression wa s detectable in the Ii-day-old mouse embryo, and the level of its mRNA increased tenfold by 15 and 17 days of gestation.