Recombinant fremstilling af terapeutiske proteiner er et centralt problemfelt inden for den moderne biomedicin. En af de væsentligste faktorer med hensyn til terapeutisk anvendelse i mennesket er de posttranslationelle modifikationer (PTM’er) af de rekombinant producerede proteiner, hvoraf glykosylering er langt den vigtigste. I de tilfælde hvor glykosylering er fundet nødvendig for funktion eller biologiske aktivivtet, er glykoprotein therapeutika generelt blevet udtrykt i den mammale celle linie CHO (Chinese hamster ovary cell). O-glykosylering er en af de mest komplekst regulerede PTM’er, men også en af de mindst udforskede. Indtil videre kræves der mammale celler til O-glykosylering. Der er derfor stigende interesse for at finde alternativer til mammale celle til produktion af skræddersyede rekombinante proteiner med human glykosylering. Der er opnået store fremskridt indenfor design af N-glykosylering i lavere eukaryoter og selv i prokaryoter, men manipulering of human O-glykosyleringer stadig i sin begyndelse. I dag er mammale celler i praksis eneste kilde til opnåelse af human O-glykosylering. Insekt- og gærceller producerer O-glycosylering, der er inkompatible med anvendelse i mennesket, dog er gær-typen Pichia for nyligt blevet genetisk modificeret til at udføre det første trin i human O-glykosylering. Dette review indeholder en gennemgang af tidligere og nuværende tiltag indenfor genetisk modifikation af værtsceller til produktion af proteiner med human N- og Oglykosylering, inklusiv planteceller som nye spirende alternative platformer. Planterer både billige og sikre produktionsorganismer, der nemt kan opskaleres, og de producerer ikke har den type O-glykosylering, der findes i mammale celler. Disse egenskaber muliggør potentielt set produktion af skræddersyede proteiner med human glykosylering i planteceller. ; Recombinant expression of therapeutic proteins is one of the major tasks in modern biomedicine. One of the most important factors with respect to therapeutic use in human is posttranslational modifications (PTMs) of the recombinant proteins, of which protein glycosylation is by far the most important to address. Whenever glycosylation has been found to be an important PTM for function or bioactivity, human therapeutics have generally been produced in mammalian Chinese hamster ovary (CHO) cell line. Oglycosylation is one of the most complex regulated PTMs of proteins but also one of the least understood. Currently, mammalian cells are required for human O-glycosylation. Increasing efforts have been devoted to engineering non-mammalian cells for production of recombinant proteins with “human-like” glycosylation. Substantial success has been achieved with designed N-glycosylation in both lower eukaryotes and even prokaryotes. Insect and yeast cells produce O-glycosylation incompatible with use in humans, however recently the yeast Pichia was engineered to perform the first step of human-like O-glycosylation. This review provides an overview of past and current engineering efforts of N- and Oglycosylation and addresses emerging novel promising platforms such as plants. Plants are safe and low-cost production organisms; they do not perform mammalian-type glycosylation by itself and are easily up-scalable. These features should make it possible to custom design and build capacity for human-like glycosylation in plants