期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：19
页码：8990-8994
DOI：10.1073/pnas.89.19.8990
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A systematic screen of a protein sequence data base confirms that the fibronectin type III (Fn3) domain is widely distributed among animal proteins and occurs also in several bacterial carbohydrate-splitting enzymes. The motif has yet to be identified in proteins from plants or fungi. All indications are that the bacterial sequences are much too similar to the animal type to be the result of conventional vertical descent. Rather, it is likely that the bacterial units were initially acquired from an animal source and are being spread further by horizontal transfers between distantly related bacteria.
