A hydroxyproline-rich protein in the soybean cell wall

• Published in: Proceedings of the National Academy of Sciences - PNAS 1988-02, Vol.85 (4), p.1082-1085
• Main Authors: Averyhart-Fullard, V, Datta, K, Marcus, A
• Format: Article
• Language: English
• ISSN: 0027-8424; 1091-6490

A cDNA clone that hybridizes to an mRNA (1A10) that accumulates to a substantial level in the axis of the germinating soybean seed was sequenced. The amino acid sequence of the clone indicates an almost perfect repeat of Pro-Pro-Val-Tyr-Lys resulting in a protein containing 40% proline and lacking serine and histidine. On the likelihood that such a protein might be a hydroxyproline-rich cell-wall glycoprotein (HRGP), cell walls of a soybean cell culture were extracted by procedures used to obtain soluble basic cell-wall glycoproteins, and the proteins were fractionated and purified. A 33-kDa protein (and possibly a 28-kDa protein) was obtained that has an amino acid distribution similar to that of the cDNA clone. The protein lacks histidine and serine and contains 20% hydroxyproline and 20% proline. The HRGP is thus distinct both in its amino acid content and in its pentameric repeat of Pro-Pro-Val-Tyr-Lys, with half of the prolines being hydroxylated.