DNA analysis with BeadChip format, combined with computerized data entry and analysis, permits the prediction of minor blood group antigens.

It has been shown that microarray technology can be used to type DNA and detect new alleles in donor cohorts.

No abstract

The protein kinase activity of human insulin receptors purified from Sf9 insect cells after infection with a recombinant baculovirus was evaluated. The following exper-imental observations led to the unexpected conclusion that this receptor protein catalyzes both serine and tyrosine autophos- The insulin receptor is one of a number of growth factor receptors with intrinsic tyrosine kinase activity that can be activated upon binding of appropriate peptide ligands (1). Binding of insulin to its receptor also causes rapid phosphorylation of the tyrosine residues of the insulin receptor (3 subunit itself (2-4), which in turn further activates the tyrosine kinase activity (5, 6). In intact cells, insulin causes receptor phosphorylation on tyrosine as well as serine and threonine residues (2). Protein kinase C or protein kinases activated by this enzyme can phosphorylate the serine and threonine residues of the insulin receptor in intact cells (7,8). Stimulation of serine phosphorylation of the insulin receptor by phorbol esters appears to correlate with inhibition of the insulin-stimulated tyrosine kinase activity ofthe receptor (8).Thus, phosphorylation ofthe serine and threonine residues of the insulin receptor may regulate insulin signaling by modulating receptor tyrosine kinase activity. Several laboratory groups have reported the detection of an insulin-stimulated and receptor-associated serine/ threonine kinase activity using the receptor itself as substrate, in partially purified (9-14) or affinity-purified (15) insulin receptor preparations.

Glutamate receptor ion channels are colocalized in postsynaptic densities with Ca2+/calmodulindependent protein kinase H (CaM-kinase II), which can phosphorylate and strongly enhance non-N-methyl-D-aspartate (NMDA) glutamate receptor current. In this study, CaMkinase II enhanced kainate currents of expressed glutamate receptor 6 in 293 cells and of wild-type glutamate receptor 1, but not the Ser-627 to Ala mutant, in Xenopus oocytes. A synthetic peptide corresponding to residues 620-638 in GluRl was phosphorylated in vitro by CaM-kinase II but not by cAMP-dependent protein kinase or protein kinase C. The 32P-labeled peptide map ofthis synthetic peptide appears to be the same as the two-dimensional peptide map of a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) glutamate receptors phosphorylated in cultured hippocampal neurons by CaM-kinase II described elsewhere. This CaM-kinase II regulatory phosphorylation site is conserved in all AMPA/ kainate-type glutamate receptors, and its phosphorylation may be important in enhancing postsynaptic responsiveness as occurs during synaptic plasticity.Neural tissues are the most abundant sources for many protein kinases and phosphatases, and phosphorylation of ion channels is an important mechanism for modulating the excitability of neurons (1, 2). The major excitatory neurotransmitter in mammalian brain is glutamate, and the recent cloning of the glutamate receptor (GluR) family of ion channels makes them available for studies of their regulation by phosphorylation.

No abstract

Rasmussen's encephalitis is a childhood disease resulting in intractable seizures associated with hippocampal and neocortical inflammation. An autoantibody against the GluR3 subunit of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors is implicated in the pathophysiology of Rasmussen's encephalitis. AMPA receptors mediate excitatory neurotransmission in the brain and contain combinations of four subunits (GluR1-4). Although the distributions of GluR1, GluR2, and GluR4 are known in some detail, the cellular distribution of GluR3 in the mammalian brain remains to be described. We developed and characterized a GluR3-specific monoclonal antibody and quantified the cellular distribution of GluR3 in CA1 of the rat hippocampus. GluR3 immunoreactivity was detected in all pyramidal neurons and astrocytes and in most interneurons. We quantified the intensity of GluR3 immunoreactivity in interneuron subtypes defined by their calcium-binding protein content. GluR3 immunofluorescence, but not GluR1 or GluR2 immunofluorescence, was significantly elevated in somata of parvalbumin-containing interneurons compared to pyramidal somata. Strikingly, increased GluR3 immunofluorescence was not observed in calbindin- and calretinin-containing interneurons. Furthermore, 24% of parvalbumin-containing interneurons could be distinguished from surrounding neurons based on their intense GluR3 immunoreactivity. This subpopulation had significantly elevated GluR3 immunoreactivity compared to the rest of parvalbumin-containing interneurons. Electron microscopy revealed enriched GluR3 immunoreactivity in parvalbumin-containing perikarya at cytoplasmic and postsynaptic sites. Parvalbumin-containing interneurons, potent inhibitors of cortical pyramidal neurons, are vulnerable in the brains of epileptic patients. Our findings suggest that the somata of these interneurons are enriched in GluR3, which may render them vulnerable to pathological states such as epilepsy and Rasmussen's encephalitis.

No abstract