The following enzyme is required for the hexose monophosphate shunt pathway:
Glucose-6-phosphate is oxidized by NADP+ dependent Glucose-6-phosphate dehydrogenase (GPD). 6-phospho glucono lactone is formed.
One molecule of NADPH is formed in the reaction. This is the rate-limiting step. Regulation is effected by this enzyme
 
Reference: Vasudevan 7th  ed, pg 130
Glucose-6-phosphatase
Phosphorylase
Aldolase
Glucose-6-phosphate dehydrogenase