Transgenic plants expressing cobalamin binding proteins

Abstract

The present invention relates to the use of transgenic plants for the expression of vitamin B12 (cobalamin) binding proteins. Plant cells are transformed with nucleotide sequences adapted for expression and secretion of vitamin B12 binding proteins. The present invention also relates to the use of recombinant vitamin B12 binding proteins from plants in analytical tests and treatment of vitamin B12 deficiency. Also disclosed is a method for purification of recombinant vitamin B12 binding proteins.

What is claimed is: 
     
         1 . A composition, the composition comprising intrinsic factor with plant specific glycosylation on the intrinsic factor, wherein all of the intrinsic factor in the composition is in the apo form. 
     
     
         2 . The composition of  claim 1 , further comprising one or more pharmaceutically acceptable diluents, excipients, and/or carriers. 
     
     
         3 . The composition of  claim 1 , wherein the composition is suitable for oral use. 
     
     
         4 . A composition, the composition comprising intrinsic factor, wherein all of the intrinsic factor in the composition is in the apo form within a plant cell. 
     
     
         5 . The composition of  claim 4 , wherein the intrinsic factor is capable of binding cobalamin or an analog thereof. 
     
     
         6 . The composition of  claim 5 , wherein the intrinsic factor has the capacity to bind to the cubilin receptor in vivo. 
     
     
         7 . The composition of  claim 4 , further comprising one or more pharmaceutically acceptable diluents, excipients, and/or carriers. 
     
     
         8 . The composition of  claim 4 , wherein the composition is suitable for oral use. 
     
     
         9 . A composition, the composition comprising intrinsic factor and a plant specific carbohydrate chain on the intrinsic factor, wherein all of the intrinsic factor is in the apo form. 
     
     
         10 . The composition of  claim 9 , further comprising one or more pharmaceutically acceptable diluents, excipients, and/or carriers. 
     
     
         11 . The composition of  claim 9 , wherein the composition is suitable for oral use. 
     
     
         12 . A method of producing functional recombinant intrinsic factor, the method comprising expressing intrinsic factor in a plant, wherein the intrinsic factor binds vitamin B12. 
     
     
         13 . The method of  claim 12 , wherein the plant is “Generally Recognized As Safe” (GRAS). 
     
     
         14 . The method of  claim 12 , wherein the intrinsic factor, when bound to B12, is capable of binding cubilin.