Determining the correlation between structure and function for the Drosophila insulin receptor substrate chico

The Drosophila gene chico codes for the homolog of the vertebrate insulin receptor substrate (IRS) family of proteins. CHICO is phosphorylated by an activated insulin receptor and signals to several downstream signalling pathways through various predicted binding domains. To investigate how the structure of CHICO contributes to its function, an ethyl methanesulfonate (EMS) screen was performed to generate novel chico alleles. One novel allele, chico13063, was recovered out of 22,072 lines screened. This allele displayed numerous chico phenotypes including: reduced body size, weight, wing size, and developmental time delay. These phenotypes were stronger in the chico13063 allele than the null allele, chico1 and the deficiency, Df(2L)flp 147E. The chico13063 coding region was sequenced and no genetic lesions were found, suggesting the mutation is in the regulatory region. Future work would be to sequence putative regulatory regions of chico and examine the expression levels of CHICO in the chico13063 mutant.