The exosporium is the outer surface layer of mature spores.
This Cot protein share similar sequences with other spore coat proteins, and their putative determinants are believed to include bxpC, lunA, exsA, etc.
CotY, ExsY and CotB are homologues of Bacillus subtilis outer spore coat proteins, but ExsF and ExsK are specific to B. anthracis and other members of the Bacillus cereus group.
[1] The protein ywdL has been identified in B. cereus as important for exosporium formation.
ΔywdL spores have abnormal germination properties, such as the inability to respond to standard chemical means of inducing germination by treatment with calcium dipicolinate.