This proposal requests funds for a replacement protein sequencer for the UCSD Biology Department. The existing sequencer has operated for 10 years and has analyzed more than 1650 samples for 130 laboratories. However, existing sequencer is obsolete and the day is rapidly approaching when it will no longer be repairable. In addition, improvements in sequencer technology and chemistry have been made since the purchase of the existing sequencer. Cycle times have been shortened by 50%, reagent consumption has been reduced, sensitivity has been improved from 100 pmole to less than 2 pmole of sample, and the introduction of multiple cartridges offers significantly increased sample throughput. The use of the protein sequence information includes the necessary first step in the construction of oligonucleotide probes and eventual cloning of genes, investigation of the posttranslational modifications in proteins which are important for protein function, identification of functionally important regions of proteins after amino acid modifications and peptide isolation, investigations of evolution in genes from various species, and the identification of proteins as novel, new proteins by comparing N-terminal sequence data with the available protein sequence data bases.