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The fatty acylation and plasma membrane targeting characteristics of p59(super fyn) are responsible for the ability of the src homology (SH) 4 domain to bind to TCR proteins. Four amino acid residues are necessary for the proper binding of p59(super fyn) to TCR. The amino acids are present in p59(super fyn) and other src family of tyrosine kinases that bind to the immune-receptor tyrosine-based activation motif. The amino acids are also necessary for proper fatty acylation and plasma membrane targeting.

Nsp1p associates with the various nuclear pore complex (NPC) structures and is involved in multiple interactions at the NPC. The carboxy-terminal domain demonstrating heptad repeats of the nuclear pore protein, Nup82, binds to Nsp1p. In yeast cells where Nup82p is absent, cell growth is inhibited and a disorder is observed in the poly(A)+ RNA export.

A multivalent radioligand having sulfoglucuronylneolacto (SGNL)-oligosaccharides covalently attached to a radioiodinated carrier protein, bovine serum albumin, was constructed. The radioligand was prepared to probe the presence of SGNL-oligosaccharide receptor in the peripheral nervous system (PNS). The properties of a complementary SGNL-specific binding site on PNS myelin is presented.

A study was conducted on the effects of tetracaine, procaine and QX314 on Ca2+ release by the sarcoplasmic reticulum (SR). Purified skeletal muscle Ca2+ release channel complex was incorporated into planar lipid bilayers and examined. Results indicate adding tetracaine andprocaine to the bilayer's cytoplasmic side or SR lumenal side caused a reduction in the activity of Ca2+- and ATP-gated channels. Both drugs inhibitedchannel activity through binding with at least two cooperativelty interacting high-affinity regulatory sites of the SR Ca2+ release channel.

The mechanism of cooperative channel gating is being investigated through the activation of the nucleotide gate component of these channels. One research team was able to study covalent activation of cyclic nucleotide-gated channels by using 8-p-azidophenyacylthio-cGMP in place of cyclic GMP. Other researchers have also characterized the way the nucleotide component regulates ion currents through the channels using the Hill equation with values lower than one for the Hill constant.

Voltage-gated potassium channels are composed of four subunits. Voltage-dependent activation of these channels consists of a depolarization-triggered series of charge-carrying steps that occur in each subunit. These major charge-carrying steps are followed by cooperative step(s) that lead to channel opening. Unlike the late cooperative steps, the major charge-carrying steps have been proposed to occur independently in each of the channel subunits. In this paper, we examine this further. We showed earlier that the two major charge-carrying steps are associated with two sequential outward transmembrane movements of the charged S4 segment. We now use voltage clamp fluorometry to monitor these S4 movements in individual subunits of heterotetrameric channels. In this way, we estimate the influence of one subunit's S4 movement on another's when the energetics of their transmembrane movements differ. Our results show that the first S4 movement occurs independently in each subunit, while the second occurs cooperatively. At least part of the cooperativity appears to be intrinsic to the second S4 charge-carrying rearrangement. Such cooperativity in gating of voltage-dependent channels has great physiological relevance since it can affect both action potential threshold and rate of propagation. KEY WORDS: potassium channel * cooperativity * fluorescence * voltage-sensing * gating

Introducing allosteric interactions between adjacent ryanodine receptors (RyRs) can stabilize the inactive state and result in cooperativity among the different RyRs' calcium binding locations. The experiment shows that such interactions between neighboring RyRs through the process of calcium-induced calcium release can result in a stable local control of the calcium release by the sarcoplasmic reticulum. The simulation further reveals that the process can be achieved even by an RyR with an unstable gating scheme.