IGF-1 receptors of fetal brain are enriched ib the growth cone and contain an apparently novel b subunit

S. QUIROGA; R. GAROFALO; K.H. PFENNINGER

Proceedings of the National Academy of Sciences (PNAS-USA)

Año: 1995 vol. 92 p. 4309 - 4309

font face="Courier" size="3"> ABSTRACT Nerve growth cones isolated from fetal rat brain are highly enriched in a 97-kDa glycoprotein, termed betagc, that comigrates with the beta subunit of the IGF-I receptor upon two-dimensional PAGE and is disulfide-linked to this receptor´s alpha subunit. Antibodies prepared to a conserved domain shared by the insulin and IGF-I receptor beta subunits (AbP2) or to betagc were used to study receptor distribution further. Subcellular fractionation of the fetal brain segregated most AbP2 immunoreactivity away from growth cones, whereas most betagc immunoreactivity copurified with growth cones. Experiments involving ligand-activated receptor autophosphorylation confirmed the concentration of IGF-I but notof insulin receptors in growth cone fractions. These results indicate the enrichment of IGF-