No abstract

Atrial natriuretic peptide (ANP), a hormone secreted from mammalian atria, regulates the homoeostatic balance of body fluid and blood pressure. ANP-like immunoreactivity is also present in the brain, suggesting that the peptide functions as a neuropeptide. We report here identification in porcine brain of a novel peptide of 26 amino-acid residues, eliciting a pharmacological spectrum very similar to that of ANP, such as natriuretic-diuretic, hypotensive and chick rectum relaxant activities. The complete amino-acid sequence determined for the peptide is remarkably similar to but definitely distinct from the known sequence of ANP, indicating that the genes for the two are distinct. Thus, we have designated the peptide 'brain natriuretic peptide' (BNP). The occurrence of BNP with ANP in mammalian brain suggests the possibility that the physiological functions so far thought to be mediated by ANP may be regulated through a dual mechanism involving both ANP and BNP.

The sequence of 5,037 amino acids composing the ryanodine receptor from rabbit skeletal muscle sarcoplasmic reticulum has been deduced by cloning and sequencing the complementary DNA. The predicted structure suggests that the calcium release channel activity resides in the C-terminal region of the receptor molecule, whereas the remaining portion constitutes the 'foot' structure spanning the junctional gap between the sarcoplasmic reticulum and the transverse tubule.

Cloning and sequence analysis of cDNA for the Electrophorus electricus electroplax sodium channel indicate that this protein, consisting of 1,820 amino acid residues, exhibits four repeated homology units, which are presumably oriented in a pseudosymmetric fashion across the membrane. Each homology unit contains a unique segment with clustered positively charged residues, which may be involved in the gating structure, possibly in conjunction with negatively charged residues clustered elsewhere.