This invention is to provide a process for producing a
glycoprotein comprising a mammalian type
sugar chain, characterized in that the process comprises introducing an α-1,2-
mannosidase gene into a methylotrophic
yeast having a
mutation of a
sugar chain biosynthesizing
enzyme gene, so that the α-1,2-
mannosidase gene is expressed under the control of a potent
promoter in the
yeast; culturing in a medium the methylotrophic
yeast cells with a
heterologous gene transferred thereinto; and obtaining the
glycoprotein comprising a mammalian type
sugar chain from the culture. Using the newly created methylotrophic yeast having a sugar chain
mutation, a neutral sugar chain identical with a
high mannose type sugar chain produced by mammalian cells such as human cells, or a
glycoprotein comprising such a neutral sugar chain, can be produced in a large amount at a high purity. By introducing a mammalian type sugar chain biosynthesizing gene into the above-described
mutant, a mammalian type sugar chain, such as a
hybrid or complex, or a
protein comprising a mammalian type sugar chain can be efficiently produced.