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On molecular sieve columns the neuropeptide head activator elutes at two distinct positions corresponding to apparent mol. wts of 700 and 1400 daltons. The low mol. wt component is stable only under high ionic conditions and represents the monomeric state of the head activator. Only this form is biologically active. The higher mol. wt component, which is(More)
Hydra forced to regenerate a head releases head activator and head inhibitor during the first hours after cutting to induce head-specific growth and differentiation processes. Analysis of the size distribution demonstrated that the head-activator peptide is co-released with (a) large molecular weight carrier molecule(s) to which it is non-covalently bound.(More)
By exposing different sites of the 'head activator', different sets of antibodies were designed and produced which recognised either the amino or the carboxy terminus of the free 'head activator', which reacted with 'head activator' in a tissue-fixed conformation, or which bound to the 'head-activator' sequence, if it was part of a larger precursor-like(More)
New analogues of head activator were produced for receptor and radioimmunoassay studies. The precursor molecules [(4'-I)Phe11] head activator and [Tyr11] head activator were synthesised for catalytic tritiation and iodination, respectively. With the tracer [(3,5-125 I2)Tyr11] head activator the sensitivity range of the radioimmunoassay was 5-100 fmol.
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