... pointed to a role for components of the ER–Golgi vesicle transport. Through the use of mark-ers for the ER (PDI) and the Golgi apparatus(GM130, p230), the phosphorylated isoforms of the K650M mutant ... charac-terized by a variable but marked reduction in the fullyglycosylated isoform and a significant increase in the nonglycosylated and partially glycosylated isoforms.This defective maturation of the receptor ... for long-bone dysplasias inclu-ding achondroplasia (ACH), the most common form of dwarfism in humans, the milder form hypochondropla-sia and the neonatal lethal form thanatophoric dyspla-sia...