# C3, C4, C5  FUNCTIONAL FORMS AND MOLECULAR PROPERTIES

> **NIH NIH R01** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 1990 · $96,751

## Abstract

Our-long term objective has been to study the properties of C3,
C4, and C5 that are related to their structural integrity and
functionality.  These proteins are components of the complement
system, whose apparent main function is to help defend the human
body against bacteria, viruses, yeast and foreign particles or
substances.  All three proteins have to be activated and
fragmented to fulfill a variety of their physiological functions.
Most of the fragments have the capacity to trigger cellular
responses, some may participate even in an immune regulation.
An additional stability to functional forms of C3, C4, and C5, or
their fragments, is being conferred by disulfide bonds.

The specific aims of this project are:

(1)  To demonstrate the effect of distribution of disulfide linkages
on conformation of the domains of C3 and C4, and to localize
interchain, inter- and intradomains linkages in C3, C4, and C5.
Determination of disulfide-bonding patterns will allow to
understand the spacial arrangements within the polypeptide
chains, and should provide another evidence for the importance of
disulfide bonds for the structural and functional integrity in
homologous proteins.  The study of the interaction of highly cross-
linked domains, and other domains, with physiological ligands will
be attempted.

(2)  To elucidate the fragmentation pathway of the fluid-phase
C3b, the activated form of C3.  The physiologically relevant
cleavage products generated in the absence of acceptor surfaces
will be isolated by immunoaffinity chromatography and
characterized by SDS-PAGE and by N-terminal sequence analysis.
We propose to identify the enzyme responsible for the cleavage of
the fluid-phase iC3b into C3c and C3d-containing fragments.
Biological activities of the fluid-phase fragments, specifically
those of C3d,g dimer and C3c, will be investigated.

## Key facts

- **NIH application ID:** 3128690
- **Project number:** 5R01AI019319-06
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **SAM.gov UEI:** LL8GLEVH6MG3
- **Principal Investigator:** JARMILA JANATA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $96,751
- **Award type:** 5
- **Project period:** 1983-07-01 → 1991-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3128690

## Citation

> US National Institutes of Health, RePORTER application 3128690, C3, C4, C5  FUNCTIONAL FORMS AND MOLECULAR PROPERTIES (5R01AI019319-06). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3128690. Licensed CC0.

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