Production of Recombinant Proteins in D. discoideum

Actin accounts for ca. 8% of the total protein of a D. discoideum cell. There are at least 23 functional actin genes [59], and promoters and transcription terminators iso- 

Unfortunately, there is no promoter available that allows for the induction of protein expression in response to an extracellular signal. Thus, if regulated expression of heterologous genes is desired, one can either use developmentaUy regulated promoters, or promoters that respond to 

A commonly used promoter active in early development is derived from the rasD gene. This promoter is promising at first glance, because it is strictly turned off during growth and can be rapidly induced by a single dose of micromolar cAMP at 6 hours after the onset of starvation (i.e., suspending the cells in phosphate buffer). 

The pMUW expression system [77] consists of two plasmids. Plasmid 1 carries the Ddp2 rep gene and a neo selection marker. Plasmid 2 does not contain a selection cassette, but has the Ddp2 origin of replication to keep the plasmid extrachromosomal it also contains a cassette for the expression of transgenes, consist- 

Plasmid pVTL2, which is another example of an extrachromosomal plasmid [83], was used to express the firefly luciferase gene under the control of various promoters. The luciferase gene can be replaced for other heterologous transgenes, which can be expressed from any D. discoideum promoter introduced into the multiple cloning site. The pVTL2 plasmid was reported to produce 10-50 copies per cell [83]. 

---

Production of Recombinant Proteins in D, discoideum 677 Table 5.2 (continued)... 

---