Cotyledons of developing P. vulgaris L. cv. Greensleeves seeds were labeled for 2-3 h with 3H-amino acids and newly synthesized phytohemagglutinin (PHA) was isolated by affinity chromatography with thyroglobulin-Sepharose. The presence of 1% Tween in the homogenate increased the yield of radioactive PHA by 50-100%. Isopycnic sucrose gradients were used to show that this detergent-released PHA was associated with the endoplasmic reticulum (ER) and pulse-chase experiments showed that the half-life of the PHA in the ER was 90-120 min. Since PHA is transiently associated with the ER and accumulates in protein bodies, this rapidly turning over pool of PHA in the ER may represent protein en route to the protein bodies. The PHA in the ER has the same sedimentation constant as mature PHA and is capable of agglutinating red blood cells. Evidently, plant cells contain membrane-bound lectins. These lectins are not necessarily functional components of the membranes with which they are associated, but may represent transport pools of lectin normally localized in other cellular compartments.
CHARACTERISTICS OF MEMBRANE BOUND LECTIN IN DEVELOPING PHASEOLUS-VULGARIS CULTIVAR GREENSLEEVES COTYLEDONS
BOLLINI R
1982
Abstract
Cotyledons of developing P. vulgaris L. cv. Greensleeves seeds were labeled for 2-3 h with 3H-amino acids and newly synthesized phytohemagglutinin (PHA) was isolated by affinity chromatography with thyroglobulin-Sepharose. The presence of 1% Tween in the homogenate increased the yield of radioactive PHA by 50-100%. Isopycnic sucrose gradients were used to show that this detergent-released PHA was associated with the endoplasmic reticulum (ER) and pulse-chase experiments showed that the half-life of the PHA in the ER was 90-120 min. Since PHA is transiently associated with the ER and accumulates in protein bodies, this rapidly turning over pool of PHA in the ER may represent protein en route to the protein bodies. The PHA in the ER has the same sedimentation constant as mature PHA and is capable of agglutinating red blood cells. Evidently, plant cells contain membrane-bound lectins. These lectins are not necessarily functional components of the membranes with which they are associated, but may represent transport pools of lectin normally localized in other cellular compartments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
