The aim of this project is to identify and characterise novel client proteins of Cdc37 in S. pombe through a synthetic lethal genetic screen. During the screen, 68 strains were initially picked out of 40,000 colonies as potentially synthetically lethal with cdc37-681, a temperature sensitive allele, at permissive temperature. When retested, 12 strains were identified as candidate strains. Mutations identified in 3 strains were found by genetic analysis to have a phenotype of their own in a cdc37⁺ background. A genomic library was transformed into each synthetic lethal mutant. wis4, msc1, nak1 and cdc7 were identified as candidate genes that rescue the various mutants. wis4 encodes a MAP3K involved in the stress-responsive signal transduction pathway; win1 encodes a closely related kinase. By crossing wis4 and win1 deletion strains with cdc37-681, it was proved that wis4 and win1 are not synthetic lethal with cdc37-681. msc1 is a multi-copy suppressor of chk1 and has a role in regulating chromatin structure. However, neither musc1 nor chk1 is synthetically lethal with cdc37-681. nak1 encodes an essential protein kinase and plays a role in the regulation of cell polarity, growth and division. But nak1ts mutants do not show synthetic lethality with cdc37-681. Cdc7 is a protein kinase essential for septation and cell division.  A known cdc7ts mutant, cdc7-24 was shown to by synthetically lethal with cdc17-68. The synthetic lethal mutation outcrossed from J322 (the strain rescued by cdc7⁺) shows the same phenotype as cdc7-24. Cdc7 is a possible Cdc37 client, but Cdc7 protein levels do not change in cdc37-681 or cdc37-184 at restrictive temperature. Cdc7 kinase activity is produced in cdc37-681 and cdc37-184, indicating that Cdc37 function is needed for Cdc7 kinase activity. The cell morphology of cdc37ts in combination with GFP-tagged cdc7 is similar to that of cdc7ts mutants and differs from the cdc37ts single mutant. Cdc7 can locate to the spindle pole body in cdc37ts strains, which suggests Cdc7 localisation does not require Cdc37.