Document Type


Publication Date






Publication Title

Insect Biochemistry and Molecular Biology


spiders, spider silk, silk proteins, DNA, Spidroin, Fibroin, Repetitive protein, Concerted evolution, Araneus bicentenarius, Nephila clavipes

Subject Categories

Spiders/genetics; Evolution, Molecular; Proteins/genetics; Fibroins; DNA Primers


Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from PCR of genomic DNA from Araneus bicentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.


NOTICE: this is the author’s version of a work that was accepted for publication in Insect Chemistry and Molecular Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Insect Chemistry and Molecular Biology 28.3 (1998): 121-130.