The current invention provides methods for producing a polypeptide as inclusion bodies in bacterial host cells. The present methods are carried out by forming a gene construct comprising the genetic sequence encoding a polypeptide operatively linked to that of an inclusion partner protein, such that host cells comprising the gene construct produce the polypeptide as intracellular inclusion bodies thereby facilitating rapid isolation and purification of recombinant proteins. The invention further provides methods for producing protein molecular weight ladders for us in protein gel electrophoresis, as well as proteins and protein molecular weight ladders produced by these methods.