Proctolin is an endogenous pentapeptide (Arg-Tyr-Leu-Pro-Thr) that acts as an excitatory neuromodulator in crustaceans and insects [1].
Its receptor is a G-protein coupled receptor (GPCR) [1].

Proctolin stimulates resting systems and raises action potential frequency and amplitude [1]. It also enhances muscular contraction amplitude. Proctolin functions as a neuromodulator and maybe a neurohormone in arthropods. It doesn't seem to perform like a conventional neurotransmitter [2]. The first insect neuropeptide to be chemically and sequence-characterized is proctolin, a pentapeptide containing the mature peptide RYLPT. CG7105 in Drosophila melanogaster was the first proctolin precursor gene to be identified. Even so, prior research indicated that B lacks proctolin. Mori, a proteomic investigation of B recently revealed the presence of this pentapeptide. mori wings. A similar gene was found in the Borer borer, but the Bombyx mori Proctolin gene does not provide mature peptides due to the absence of cleavage sites at the N- and C-termini of the RYLPT sequence. As a result, it is thought that neither Bombyx mori nor Borer borer have shown signs of having real Proctolin[3].

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The physiological role of proctolin as a neuromodulator is well characterized. It can increase the frequency of action potentials, increase the amplitude of muscle contraction, and initiate activity in quiescent systems [1].

In the American lobster Homarus americanus, three daily injections of proctolin to temporarily raise hemal concentrations to 10⁻⁶ M resulted in significant differential expression of 255 transcripts (adjusted p < 0.05) compared to saline-injected controls. Of these transcripts, 79 (31%) had reliable protein annotations [1].
Among the annotated transcripts, 80% were upregulated and largely included proteins involved in immune and neural systems. Neural transcripts included annexin, proteins involved in gap junctions between electrically connected neurons (adjusted p < 0.05, +3 log₂ fold change), and transient receptor potential channels (TRPA1, TRP pyrexia) (adjusted p < 0.05, +3 log₂ fold change) [1].
The greatest log₂ fold change was observed in three transcripts annotating to anti-lipopolysaccharide factors (ALFs) (adjusted p < 0.001, +5 log₂ fold change), which are peptides with potent anticoagulation and antimicrobial abilities. A stress-activated protein kinase identified in another crustacean immune response [UniprotKB: G0ZJ53] was also upregulated (adjusted p < 0.001, +4 log₂ fold change) [1].
These results indicate a relationship between hemal proctolin and increased synthesis of antimicrobial proteins, suggesting a novel role for proctolin in innate immunity pathways. This neuromodulator may be multi-faceted in its role as a signaling molecule, acting on both neural and immune systems [1].

Adult Homarus americanus were purchased from local commercial fisherman and held in ambient running seawater tanks (10.29 ± 0.01°C) at the Northeastern University Marine Science Center. Lobsters were not fed prior to experimentation [1].
Individuals were subjected to once-daily hormone treatments of proctolin (Arg-Tyr-Leu-Pro-Thr) for a three-day period. Proctolin was injected in physiological saline to temporarily increase systemic proctolin concentration to 10⁻⁶ M, based on standard hemolymph/bodyweight calculations and physiologically relevant concentration levels. Control treatments received physiological saline injections. The treatment period was selected based on time frames of ion channel turnover, a process that can take hours to days [1].
Efficacy of injections increasing systemic proctolin was confirmed by quantitative mass spectrometry [1].
Four different tissue types were collected from live Homarus americanus: (1) abdominal nerve cord (n = 3), (2) supraesophageal ganglion (the "brain") (n = 1), (3) heart and pericardial cavity with neurosecretory pericardial organ (n = 3), (4) muscle tissue from abdominal muscles (n = 3). Samples were removed with forceps and surgical scissors, flash-frozen in TRI reagent with liquid nitrogen, and pulverized with RNase-DNase-free pestles [1].

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Adult Homarus americanus were purchased from local commercial fisherman and held in ambient running seawater tanks (10.29 ± 0.01°C) at the Northeastern University Marine Science Center. Lobsters were not fed prior to experimentation [1].
Individuals were subjected to once-daily hormone treatments of proctolin (Arg-Tyr-Leu-Pro-Thr) for a three-day period. Proctolin was injected in physiological saline to temporarily increase systemic proctolin concentration to 10⁻⁶ M, based on standard hemolymph/bodyweight calculations and physiologically relevant concentration levels. Control treatments received physiological saline injections. The treatment period was selected based on time frames of ion channel turnover, a process that can take hours to days [1].
Efficacy of injections increasing systemic proctolin was confirmed by quantitative mass spectrometry [1].
Four different tissue types were collected from live Homarus americanus: (1) abdominal nerve cord (n = 3), (2) supraesophageal ganglion (the "brain") (n = 1), (3) heart and pericardial cavity with neurosecretory pericardial organ (n = 3), (4) muscle tissue from abdominal muscles (n = 3). Samples were removed with forceps and surgical scissors, flash-frozen in TRI reagent with liquid nitrogen, and pulverized with RNase-DNase-free pestles [1].

[1]. De novo transcriptome assembly for the lobster Homarus americanus and characterization of differential gene expression across nervous system tissues. BMC Genomics. 2016 Jan 16;17:63.

[2]. Proctolin: a review with emphasis on insects. J Neurobiol. 1989 Jul;20(5):470-96.

[3]. Identification and expression profiles of neuropeptides and their G protein-coupled receptors in the rice stem borer Chilo suppressalis. Sci Rep. 2016 Jun 29;6:28976.

Proctolin are peptides.

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Proctolin is an endogenous pentapeptide that acts as an excitatory neuromodulator. Its physiological role as a neuromodulator is well characterized in crustaceans and insects [1].
Proctolin can increase the frequency of action potentials, increase the amplitude of muscle contraction, and initiate activity in quiescent systems. It is also accepted to function at a system-wide hormonal level, a context in which this neuropeptide remains poorly understood [1].
The identified receptor for proctolin is a G-protein coupled receptor (GPCR), suggesting a mechanism by which proctolin may regulate various cellular responses through second messenger systems [1].
This study investigated the role of proctolin as a hormonal regulator of gene expression by treating lobsters with three daily exogenous proctolin injections to temporarily raise hemal concentrations. The results implicate a novel role for hemal proctolin in innate immunity pathways, suggesting this neuromodulator may be multi-faceted in its role as a signaling molecule and act on both neural and immune systems [1].
The upregulation of anti-lipopolysaccharide factors (ALFs) and stress-activated protein kinase in response to proctolin treatment indicates a relationship between this neuromodulator and increased synthesis of antimicrobial proteins, expanding our understanding of proctolin's physiological functions beyond neuromodulation [1].

648.36

57966-42-4

123786

White to off-white solid powder

2.832

9

10

17

46

1080

6

N/C(=N/CCCC(C(NC(C(NC(C(N1CCCC1C(NC(C(=O)O)C(O)C)=O)=O)CC(C)C)=O)CC1=CC=C(O)C=C1)=O)N)/N

KKUPPLMEDQDAJX-UEHMALFGSA-N

InChI=1S/C30H48N8O8/c1-16(2)14-22(28(44)38-13-5-7-23(38)27(43)37-24(17(3)39)29(45)46)36-26(42)21(15-18-8-10-19(40)11-9-18)35-25(41)20(31)6-4-12-34-30(32)33/h8-11,16-17,20-24,39-40H,4-7,12-15,31H2,1-3H3,(H,35,41)(H,36,42)(H,37,43)(H,45,46)(H4,32,33,34)/t17-,20+,21+,22+,23+,24+/m1/s1

(2S,3R)-2-[[(2S)-1-[(2S)-2-[[(2S)-2-[[(2S)-2-amino-5-(diaminomethylideneamino)pentanoyl]amino]-3-(4-hydroxyphenyl)propanoyl]amino]-4-methylpentanoyl]pyrrolidine-2-carbonyl]amino]-3-hydroxybutanoic acid

Gut factor Proctolin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~100 mg/mL (~154.14 mM)

Solubility in Formulation 1: ≥ 100 mg/mL (154.14 mM) (saturation unknown) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)