cecER ~600-1,100: pmaER ~550-900: tubER ~250-400: BSC1 cell cisternae 1,000±300 ribosomes/μm^2
||West M, Zurek N, Hoenger A, Voeltz GK. A 3D analysis of yeast ER structure reveals how ER domains are organized by membrane curvature. J Cell Biol. 2011 Apr 18 193(2):333-46. doi: 10.1083/jcb.201011039 p.341PubMed ID21502358
||L. Lu, M.S. Ladinsky, T. Kirchhausen. 2009. Cisternal organization of the endoplasmic reticulum during mitosis. Mol. Biol. Cell. 20:3471–3480. doi:10.1091/mbc.E09-04-0327PubMed ID19494040
||Abstract: "[Investigators] analyzed the structure of yeast endoplasmic reticulum (ER) during six sequential stages of budding by electron tomography to reveal a three-dimensional portrait of ER organization during inheritance at a nanometer resolution. [They] have determined the distribution, dimensions, and ribosome densities of structurally distinct but continuous ER domains during multiple stages of budding with and without the tubule-shaping proteins, reticulons (Rtns) and Yop1."
||P.341 left column: "[Investigators] show that cecER and the pmaER (cytoplasmic face) have the highest ribosome densities ranging from ∼600 to 1,100 ribosomes/µm^2 for the cecER and ∼550 to 900 ribosomes/µm^2 for the pmaER (cytoplasmic face). The ribosome density of yeast cecER is similar to that of mitotic mammalian BSC1 cell cisternae, which was determined by similar methods (1,000 ± 300 µm^2, primary source). The tubER is bound by ribosomes, although it does have less bound ribosomes than the other domains (typically ∼250–400 ribosomes/µm^2 density for tubER, Fig. 5 E). ER ribosome densities are generally lower in the bud than in the mother, suggesting that ribosomes may dissociate and then need to reassociate during inheritance (compare densities in Fig. 5, E and F). Together, these data demonstrate that tubER does have less bound ribosomes than cecER and pmaER. However, membrane curvature alone does not define ER ribosome density because pmaER and cecER have very similar levels of bound ribosomes."