a di-trans,poly-cis-dolichyl phosphate + GDP-alpha-D-mannose <=> a di-trans,poly-cis-dolichyl beta-D-mannosyl phosphate + GDP
a di-trans,poly-cis-dolichyl phosphate + gdp-alpha-d-mannose <=> a di-trans,poly-cis-dolichyl beta-d-mannosyl phosphate + gdp