Assembly, secretion, and vacuolar delivery of a hybrid immunoglobulin in plants
UNSPECIFIED. (2000) Assembly, secretion, and vacuolar delivery of a hybrid immunoglobulin in plants. PLANT PHYSIOLOGY, 123 (4). pp. 1483-1493. ISSN 0032-0889Full text not available from this repository.
Secretory immunoglobulin (Ig) A is a decameric Ig composed of four a-heavy chains, four light chains, a joining CT) chain, and a secretory component (SC). The heavy and light chains form two tetrameric Ig molecules that are joined by the I chain and associate with the SC. Expression of a secretory monoclonal antibody in tobacco (Nicotiana tabacum) has been described: this molecule (secretory IgA/G [SIgA/G]) was modified by having a hybrid heavy chain sequence consisting of IgG gamma-chain domains linked to constant region domains of an IgA alpha-chain. In tobacco, about 70% of the protein assembles to its final, decameric structure. We show here that SIgA/G assembly and secretion are slow, with only approximately 10% of the newly synthesized molecules being secreted after 24 h and the bulk probably remaining in the endoplasmic reticulum. In addition, a proportion of SIgA/G is delivered to the vacuole as at least partially assembled molecules by a process that is blocked by the membrane traffic inhibitor brefeldin A. Neither the SC nor the I chain are responsible for vacuolar delivery, because IgA/G tetramers have the same fate. The parent IgG tetrameric molecule, containing wild-type gamma-heavy chains, is instead secreted rapidly and efficiently. This strongly suggests that intracellular retention and vacuolar delivery of IgA/G is due to the rr-domains present in the hybrid alpha/gamma-heavy chains and indicates that the plant secretory system may partially deliver to the vacuole recombinant proteins expected to be secreted.
|Item Type:||Journal Article|
|Subjects:||S Agriculture > SB Plant culture|
|Journal or Publication Title:||PLANT PHYSIOLOGY|
|Publisher:||AMER SOC PLANT PHYSIOLOGISTS|
|Official Date:||August 2000|
|Number of Pages:||11|
|Page Range:||pp. 1483-1493|
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