RESUMEN
<p><b>OBJECTIVE</b>To investigate the causes and influencing factors of heterogeneity of HSA/IL1ra fusion protein expression in Pichia pastoris.</p><p><b>METHODS</b>The heterogeneity of HSA/IL1ra fusion protein expressed in Pichia pastoris was studied by removing glycosylation and inhibiting glycosylation, as well as by different ways of fusion, different clones, and different expression host.</p><p><b>RESULT</b>Glycosylation caused expression heterogeneity of fusion protein, but in SMD1168 and some GS115 clones there was no this phenomenon.</p><p><b>CONCLUSION</b>The expression heterogeneity of HSA/IL1ra fusion protein in Pichia pastoris is due to the glycosylation, and different ways of fusion, different clones, different expression host also have some impact.</p>