Subunit organization

Protein M, Number of Residues per Chain Subunit Organization... 

Many proteins consist of two or more interacting polypeptide chains of characteristic tertiary structure, each of which is commonly referred to as a subunit of the protein. Subunit organization constitutes another level in the hierarchy of protein structure, defined as the protein s quaternary (4°) structure (Figure 5.10). Questions of quaternary structure address the various kinds of subunits within a protein molecule, the number of each, and the ways in which they interact with one another. 

Desulfoviridin was found in D. gigas, D. salexigens, and D. vulgaris Hildenborough. Desulfoviridin is composed of three different subunits organized in a 0 2/3272 configuration with a total molecular mass of approximately 200 kDa. The molecular mass of the a, (3, and 7 subunits was calculated to be 50, 40, and 11 kDa, respectively (156). 

Hersckovits, T. (1988) Recent aspects of the subunit organization and dissociation of hemocyanins. 

Unlike the nucleocapsid core found in the alphaviruses, the flavivirus core is an open structure with no well-defined subunit organization. At the current resolution of flavivirus cryo-EM reconstructions, little can be said about the transmembrane domains that cross the bilayer or the possible contacts the envelope proteins might make with the underlying core (Kuhn et al, 2002). 

Fraering PC, LaVoie MJ, Ye W, Ostaszewski BL, Kimberly WT, Selkoe DJ, Wolfe MS. Detergent-dependent dissociation of active y-secretase reveals an interaction between Pen-2 and PSl-NTF and offers a model for subunit organization within the complex. Biochemistry. In Press. 

Fig. 5.2. Subunit organization of prokaryotic ATPase. The subunit stoicheiometry is based on that of thermophilic FqF, [51]. /S y 8 a b c = 3 3 l l l l 2 6. The F, portion forms a plug through the phospholipid bilayer. The c subunit assumes a hairpin shape [67].

As indicated above, the number of subunits c present in Fq has been reported to be 9-12. From consideration of the model for the proton translocation mechanism, it is believed that either 9 or 12 c subunits should be present in each Fq, and that they are presumably arranged either as three trimers or three tetramers in a ring. In accord with the ratio of 3 that has been generally accepted at least up until recently for the number of protons translocated per ATP synthesized, nine protons have to be translocated during a complete catalytic cycle, since each ofthe three (a P) pairs synthesizes an ATP thus nine c-subunits are needed, one for each translocated. However, based on the recently determined ff/ATP ratio of 4 for chloroplast and cyanobacterial ATP synthasetwelve c subunits organized in three tetramers ofc subunits would be favored. 

Lockridge, O., Eckerson, H.W. and La Du, B.N. Interchain disulfide bonds and subunit organization in human serum chohnesterase, J. Biol. Chem., 254, 8324, 1979. 

FIGURE 9-1 Subunit organization of the nicotinic ACh receptor and related pentameric ligand-gated ion channels. 

ATCase is made up of two different types of subunits. One of them is the catalytic subunit, and there are six of them organized into two trimers. The other is the regulatory subunit, which consists of six protein subunits organized into three dimers. 

HAT group HAT complex Catalytic subunit Organism Histone acetylation substrates Function... 

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