Incorporation of certain amino acid analogs into polypeptides produced
by cells which do not ordinarily provide polypeptides containing such amino acid
analogs is accomplished by subjecting the cells to growth media containing such
amino acid analogs. The degree of incorporation can be regulated by adjusting the
concentration of amino acid analogs in the media and/or by adjusting osmolality
of the media. Such incorporation allows the chemical and physical characteristics
of polypeptides to be altered and studied. In addition, nucleic acid and corresponding
proteins including a domain from a physiologically active peptide and a domain
from an extracellular matrix protein which is capable of providing a self-aggregate
are provided. Human extracellular matrix proteins capable of providing a self-aggregate
collagen are provided which are produced by prokaryotic cells. Preferred codon
usage is employed to produce extracellular matrix proteins in prokaryotics.
