De Lisle R C, Isom K S
Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City 66160, USA.
J Histochem Cytochem. 1996 Jan;44(1):57-66. doi: 10.1177/44.1.8543783.
The pancreatic zymogen granule membrane protein gp300 is the major sulfated glycoprotein of the mouse acinar cell and has been proposed to be an important structural component of the zymogen granule membrane. A prediction of this proposed function is that gp300 expression should be coordinately regulated with the digestive enzymes and appearance of zymogen granules during differentiation of acinar cells in fetal development. By Western blots and immunolocalization with a polyclonal antiserum to gp300, we found that gp300 protein expression paralleled expression of amylase and the appearance of zymogen granules in differentiating acinar cells. Lectin blots were performed to assess the glycoconjugate composition of gp300 during development. Using the fucose binding lectin Ulex europaeus I, we found that gp300 acquires this carbohydrate only postnatally, temporally correlated with weaning. In addition, gp300 showed complex changes during postnatal development in reactivity with the galactose binding lectin peanut agglutinin (PNA) and the sialic acid binding lectin Maackia amuresis (MAA). Levels of reactivity of PNA and MAA were reciprocal, suggesting that sialylation of galactose (which can block peanut agglutinin binding) was not constant on gp300 during development.
胰腺酶原颗粒膜蛋白gp300是小鼠腺泡细胞的主要硫酸化糖蛋白，有人提出它是酶原颗粒膜的重要结构成分。这一功能假设的一个推论是，在胎儿发育过程中腺泡细胞分化时，gp300的表达应与消化酶以及酶原颗粒的出现受到协同调节。通过蛋白质免疫印迹法以及使用针对gp300的多克隆抗血清进行免疫定位，我们发现gp300蛋白的表达与分化中的腺泡细胞中淀粉酶的表达以及酶原颗粒的出现相一致。进行凝集素印迹法以评估发育过程中gp300的糖缀合物组成。使用结合岩藻糖的凝集素欧洲荆豆凝集素I，我们发现gp300仅在出生后获得这种碳水化合物，在时间上与断奶相关。此外，gp300在出生后发育过程中与结合半乳糖的凝集素花生凝集素（PNA）和结合唾液酸的凝集素黑穗醋栗凝集素（MAA）的反应性呈现复杂变化。PNA和MAA的反应水平呈反比，这表明在发育过程中gp300上半乳糖的唾液酸化（可阻断花生凝集素结合）并非恒定不变。
