With the increasing demand for commercially important proteins, it has
become essential to develop more improved and efficient methods for heterologous
protein production to meet the requirements of society. Although currently there are
different host systems available for the production of proteins heterologously, still the
selection of a perfect host system becomes a tedious task if the aim is to get fully
functional protein in adequate quantity. Different types of hosts are commonly used for
heterologous protein production include Escherichia coli, Saccharomyces cerevisiae,
insect cell expression systems and various mammalian systems. Different host systems
that are used for heterologous protein expression have their own advantages and
disadvantages as in the case of bacterial systems, a good amount of protein is produced
but the quality of the protein may not be appropriate. Similarly, eukaryotic hosts also
suffer from specific merits and demerits. Different promoter systems that are used for
gene expression also influence protein production in case of both prokaryotic and
eukaryotic hosts. The selection of the appropriate host depends on the amount of the
protein, quality of the protein in terms of functional activity and its application. In this
chapter, we will discuss the principle of heterologous gene expression, different types
of hosts organism available for heterologous protein production. We will also present
the current developments and modifications which are being done in various host
systems to improve the process of protein production. We will elaborate on the
different types of vectors that are used for recombinant protein production, their
contrasting features and different promoter systems used in the vectors, importance or
promoters with respect to protein production. In addition to this, we will also elaborate
on different aspects related to the overexpression and purification of recombinant
heterologous protein and the type of tags and chromatographic techniques used for the
purification of different types of proteins.
Keywords: Affinity tags, Expression hosts, Heterologous protein production,
Over expression, Protein production, Strong promoters.
