9318193 Hogue-Angeletti We request funds toward the purchase of an instrument for matrix-assisted laser desorption, time-of-flight mass spectrometry (MALD-TOF MS) for a core laboratory with an established record of cooperation and productivity. This instrument will enable a group of investigators at Albert Einstein College of Medicine to determine protein and glycoprotein masses at high sensitivity. In addition to routine analysis of protein samples to assess molecular weight, purity, and to verify structures, the MALD-TOF mass spectrometer will be used to: 1) identify proteins involved in the formation of secretory granules and in protein sorting mechanisms; 2) study the processing of processing enzymes; 3) identify proteins and peptides secreted by ependyma and choroid plexus cells; 4) characterize the taxol binding site on microtubules; S) study the mechanism of ATP- dependent proteases; 6) analysis of proteins rapidly phosphorylated in tyrosine in response to colony stimulating factor-l.