An increasing number of studies involve integrative analysis of gnee and protein expression data, taking advantage of new technologies such as next-generation transcriptome sequencing (RNA-Seq) and highly sensitive mass spectrometry (MS). Analyses of the sequence and nature of all protein amino-termini (N-termini) within proteomes (N-terminome) in eukaryotes reveal a highly understimated occurrence of database non-annotated alternative translates, thereby increasing the already high complexity of proteomes. N-terminomics provides quantitative information on the N-terminal modification states of identified proteins in addition to enabling large-scale proteome dynamics studies. Ribosome profiling, a recently developed genomics method, enables systematic monitoring of protein translation events by deep sequencing of ribosome-protected mRNA fragments and thereby enables the study of (alternative) translation (initiation)with single codon resolution. Since the global prevalence and the in vivo regulation governing the recognition of near-cognate translation intitiation codons remains poorly understood, in this project we aim at the combined usage of N-terminomics and ribosome profiling to further explore the regulatory mechanisms governing start codon selection. Moreover, proteome-wide protein turnover and subcellular localization analyses of N-terminal protein variants will be conducted, permitting the delineation of various dynamic protein parameters and protein functionality.